A cascade heat recovery type high-temperature steam heat pump system and a heat recovery method

Abstract

The application discloses a kind of cascade heat recovery type high-temperature steam heat pump system and heat recovery method, the system mainly includes refrigerant circuit, make-up water cascade preheating circuit, high-temperature heating circulation loop and heat source water pipeline. Among them, the heated side of preheater and supercooler is sequentially connected in series on make-up water pipeline, normal temperature make-up water is heated first in preheater to absorb heat source water waste heat to carry out first temperature rise, then in supercooler to absorb the sensible heat of refrigerant deep supercooling to carry out second temperature rise;Two-stage preheated make-up water enters flash tank, mixes with liquid water in flash tank, and after further heating by main condenser, high-temperature steam is generated in flash tank. Through two-stage cascade heat recovery architecture, simultaneous realization condensing waste heat full-amount resource utilization and throttling loss deep inhibition, fundamentally improve the cycle efficiency of high-temperature steam heat pump system.

Description

Technical Field

[0001] This invention belongs to the technical field of high-temperature steam heat pumps, specifically relating to a cascade heat recovery type high-temperature steam heat pump system and heat recovery method. Background Technology

[0002] Under the dual-carbon development goals, high-temperature steam heat pumps have been widely used in industrial applications with a rigid demand for high-temperature steam above 100°C. Currently, conventional high-temperature steam heat pump systems generally adopt a quasi-two-stage compression cycle scheme with an economizer to improve cycle efficiency; however, this scheme has the following inherent technical drawbacks: Insufficient recovery of condensation waste heat: A large amount of high-grade subcooling waste heat released by refrigerant condensation is only used for a small amount of flash gas replenishment in the economizer, and the vast majority is not effectively recovered, resulting in energy waste; The effect of throttling irreversible loss suppression is limited: conventional economizer schemes can only achieve limited subcooling and cannot achieve deep subcooling. The flash loss during the throttling process is large and the cycle irreversible loss is high. Severe energy efficiency degradation under high temperature conditions: Under high temperature conditions above 85℃, the above-mentioned losses lead to a significant reduction in system cycle efficiency, low energy utilization, and a narrow range of operating conditions. The equipment input-output ratio is extremely low: the initial investment cost of existing mainstream solutions is too high and the investment recovery period is long. Summary of the Invention

[0003] To address the aforementioned problems in the existing technology, this application proposes a cascade heat recovery type high-temperature steam heat pump system and heat recovery method, which can continuously produce low-pressure saturated steam above 100℃. This cascade heat recovery type high-efficiency high-temperature steam heat pump system is widely applicable to scenarios such as industrial process steam supply, deep recovery of industrial waste heat, chemical process upgrading, and centralized heating steam peak shaving. The present invention adopts the following technical solution: According to a first aspect of this application, a cascade heat recovery type high-temperature steam heat pump system is proposed, comprising: The refrigerant circuit includes a compressor, the heat-dissipating side of the condenser, the heat-dissipating side of the subcooler, a throttling device, and an evaporator that are connected in sequence. The water supply cascade preheating circuit includes a water supply pipeline, and a preheater and a subcooler connected in series on the water supply pipeline on the heated side; the end of the water supply pipeline is connected to the first water inlet of the flash tank. A high-temperature heating circulation loop includes the flash evaporation tank, a circulating water pump, and the heated side of the condenser; the liquid water return port of the flash evaporation tank is connected to the heated side inlet of the condenser via the circulating water pump, and the heated side outlet of the condenser is connected to the second inlet of the flash evaporation tank; wherein the top of the flash evaporation tank has a steam exhaust port; The ambient temperature water is heated by the water supply stage preheating circuit and then enters the flash evaporation tank. After being further heated by the condenser in the high temperature heating cycle circuit, steam is generated in the flash evaporation tank.

[0004] This invention innovatively constructs three physical loops: refrigerant, makeup water preheating, and high-temperature heating. By using a preheater and a subcooler to preheat the cold water, the makeup water temperature entering the flash tank is significantly increased, greatly reducing the heat load on the main condenser. This breaks through the energy efficiency bottleneck of traditional heat pump steam production from the system architecture perspective.

[0005] Preferably, it also includes a heat source water pipeline, which flows sequentially through the heat release side of the evaporator and the heat release side of the preheater. External heat source water is introduced from the inlet end of the heat source water pipeline, undergoes initial heat exchange and cooling on the heat release side of the evaporator, and then flows along the heat source water pipeline into the heat release side of the preheater to release heat, thereby preheating the room temperature makeup water in the makeup water pipeline. This ensures stable heat exchange on the main circulation evaporator side and achieves full recovery of waste heat from the heat source water return water, eliminating the need for additional power equipment and resulting in a simple and reliable architecture.

[0006] More preferably, the heat source water pipeline has a branching node between the heat release side outlet of the evaporator and the heat release side inlet of the preheater, and a confluence node downstream of the heat release side outlet of the preheater. The external heat source water, cooled by the evaporator, is divided into two streams at the branching node. One portion enters the heat release side of the preheater for further heat exchange and cooling, and then merges with the other portion of external heat source water that did not enter the preheater at the confluence node and is discharged. By introducing a portion of the heat source water cooled by the evaporator into the preheater, the waste heat is extracted in a cascaded manner. The branching and confluence pipeline design ensures that the preheater has a sufficient heat source temperature difference while avoiding the problems of excessive system water resistance and pump power consumption caused by the entire heat source water flowing through the preheater, achieving dual optimization of thermal and hydraulic processes.

[0007] Preferably, the temperature difference between the makeup water entering the flash evaporation tank after being heated in two stages by the preheater and the subcooler and the temperature of the saturated water in the flash evaporation tank is no more than 20°C. This significantly reduces temperature fluctuations and irreversible flash evaporation losses caused by the introduction of low-temperature makeup water, and improves steam dryness and pressure stability.

[0008] Preferably, the refrigerant in the refrigerant circuit has a subcooling degree of not less than 25°C at the heat release side outlet of the subcooler. This significantly reduces flashover losses during the throttling process, minimizes irreversible losses in the cycle, and improves system cycle efficiency.

[0009] Preferably, the system includes at least two stages of the preheater and / or at least two stages of the subcooler arranged in series. This enables three or more stages of cascaded heat recovery, further improving waste heat recovery efficiency.

[0010] Preferably, the throttling device is selected from one of the following: electronic expansion valve, thermostatic expansion valve, capillary tube, and orifice plate throttling mechanism. Energy efficiency can be improved without the need for expensive equipment such as a two-stage compressor or complex gas supply system, system manufacturing costs are reduced, and it is easy to scale up and promote.

[0011] Preferably, the condenser, the evaporator, the subcooler, and the preheater are one of the following: plate heat exchanger, shell-and-tube heat exchanger, plate heat exchanger, and coaxial heat exchanger.

[0012] Preferably, the compressor is one of a screw compressor, a centrifugal compressor, a scroll compressor, and a reciprocating compressor.

[0013] According to a second aspect of this application, a cascade heat recovery method based on the above-mentioned high-temperature steam heat pump system is proposed, comprising the following steps: Driven by the compressor, the refrigerant circulates in the refrigerant circuit, condenses and releases high-grade heat in the condenser, and further releases sensible heat in the subcooler to form deep subcooling; In the water replenishment stage preheating circuit, the ambient temperature water flows through the preheater and the subcooler in sequence. In the preheater, it absorbs heat from the external heat source water to obtain a first temperature rise, and then absorbs the sensible heat from the subcooling of the refrigerant to obtain a second temperature rise. After completing the two-stage heating process, the replenished water enters the flash evaporation tank and is drawn into the high-temperature heating circulation loop. After absorbing the high-grade heat in the condenser, it returns to the flash evaporation tank. The high-temperature water returned to the flash evaporation tank flashes to generate steam and is then discharged.

[0014] By coupling deep subcooling of the refrigerant with staged preheating of the makeup water, the released heat is recovered to the heating cycle, realizing the full utilization of the system's waste heat.

[0015] Compared with the prior art, the beneficial results of the present invention are as follows: (1) This invention utilizes the coordinated layout of the preheater and subcooler. The ambient temperature makeup water first absorbs the waste heat of the low-grade heat source water to complete the first-stage preheating, and then absorbs the waste heat of the high-grade refrigerant condensation to complete the second-stage deep heating. All the waste heat of the heat source water and the waste heat of condensation directly discharged in the conventional system are recovered to the heating cycle, realizing the full resource utilization of redundant heat.

[0016] (2) This invention breaks through the bottleneck that conventional economizer schemes can only achieve limited subcooling. By fully coupling deep subcooling and cascade heat recovery, the refrigerant can achieve deep subcooling of more than 25°C. This significantly reduces irreversible flash loss during the throttling process and reduces irreversible losses in the cycle.

[0017] (3) The present invention reduces the temperature difference between the makeup water entering the flash evaporation tank and the saturated water inside the tank to less than 20°C through a two-stage preheating structure. This design significantly reduces the temperature fluctuation inside the flash evaporation tank caused by the low-temperature makeup water entering the flash evaporation tank, reduces the irreversible loss in the flash evaporation process, and effectively improves the stability of steam dryness and pressure.

[0018] (4) Through the synergistic effect of the above three paths, namely waste heat recovery, throttling suppression, and flash evaporation optimization, the present invention improves the overall energy utilization rate of the system by more than 20%. Without the need to add complex auxiliary equipment such as two-stage compressors, the system can still maintain stable and efficient operation under a wide range of high-temperature condensation conditions of 85℃~125℃, which significantly reduces the equipment input-output ratio and user operating costs. Attached Figure Description

[0019] The accompanying drawings provide further illustration of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Other features, objects, and advantages of this application will become more apparent from reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of a cascade heat recovery type high-temperature steam heat pump system according to a specific embodiment of the present invention.

[0020] The meanings of the numbers in the diagram are as follows: 01-Evaporator, 02-Compressor, 03-Condenser, 04-Flash tank, 05-Subcooler, 06-Throttling device, 07-Preheater, 08-Circulating water pump, 09-Heat source water pump, 10-Flash regulating valve. Detailed Implementation

[0021] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0022] In the description of this invention, it should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features.

[0023] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0024] To facilitate understanding by those skilled in the art, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0025] like Figure 1 As shown, this embodiment of the invention provides a cascade heat recovery type high-temperature steam heat pump system, which can solve the technical problem of severe energy efficiency degradation of conventional high-temperature heat pumps under high-temperature condensation conditions of 85℃~125℃. The system mainly includes a refrigerant circuit, a makeup water cascade preheating circuit, a high-temperature heating circulation circuit, and a heat source water pipeline. The core components of the system mainly include: evaporator 01, compressor 02, condenser 03, flash tank 04, subcooler 05, throttling device 06, preheater 07, and circulating water pump 08.

[0026] In a specific embodiment, the discharge port of compressor 02 is connected to the heat-releasing inlet of condenser 03; the heat-releasing outlet of condenser 03 is connected to the heat-releasing inlet of subcooler 05; the heat-releasing outlet of subcooler 05 is connected to the inlet of throttling device 06; the outlet of throttling device 06 is connected to the heat-receiving inlet of evaporator 01 via a low-pressure pipeline; and the heat-receiving outlet of evaporator 01 is reconnected to the suction port of compressor 02. The refrigerant undergoes compression, condensation, subcooling, throttling, and evaporation processes sequentially in this closed loop. In this embodiment, throttling device 06 is an electronic expansion valve; in other embodiments, throttling device 06 can also be a thermostatic expansion valve, a capillary tube, or an orifice plate throttling mechanism.

[0027] In a specific embodiment, the starting end of the ambient temperature water supply pipeline passes sequentially through the heated side of the preheater 07 and the heated side of the subcooler 05. Specifically, the outlet of the heated side of the preheater 07 is connected to the inlet of the heated side of the subcooler 05 via a pipeline; the outlet of the heated side of the subcooler 05 is connected to the first inlet of the flash tank 04 via a one-way water supply pipeline. This path ensures that the supply water must undergo primary preheating by the heat source water and secondary preheating by the refrigerant before entering the flash tank.

[0028] In a specific embodiment, the liquid water return port at the bottom of the flash evaporation tank 04 is connected to the suction end of the circulating water pump 08 via a pipe; the output end of the circulating water pump 08 is connected to the inlet on the heated side of the condenser 03; the outlet on the heated side of the condenser 03 is connected to the second inlet on the side wall of the flash evaporation tank 04 via a return pipe, and the flash evaporation regulating valve 10 is connected in series on this return pipe to throttle and reduce the pressure of the heated high-temperature water to promote flash evaporation. A steam outlet is provided at the highest point of the top of the flash evaporation tank 04 to output the saturated steam generated by flash evaporation.

[0029] The following is based on Figure 1 Describe the operation of the cascade heat recovery type high-temperature steam heat pump system of this application: Regarding the topological connections and fluid state changes in the main refrigerant circulation loop, the discharge port of compressor 02 is connected to the heat release side inlet of condenser 03. The low-temperature, low-pressure gaseous refrigerant, after being compressed by compressor 02, becomes a high-temperature, high-pressure superheated gaseous refrigerant that enters condenser 03, where it releases high-grade condensation heat and transforms into a saturated liquid refrigerant. The heat release side outlet of condenser 03 is connected to the heat release side inlet of subcooler 05. In subcooler 05, the saturated liquid refrigerant further releases sensible heat, forming a deep subcooled state. The heat release side outlet of subcooler 05 is connected to the inlet of throttling device 06. After being throttled and depressurized by throttling device 06, the refrigerant enters the heat-receiving side of evaporator 01, absorbs low-grade heat from the outside, and completely evaporates into a gaseous state. Finally, the heat-receiving side outlet of evaporator 01 is reconnected to the suction port of compressor 02, completing a closed thermodynamic cycle.

[0030] In the architecture design of the water replenishment stage preheating and high-temperature heating cycle, a two-stage preheating water circuit is constructed to fully recover waste heat. The heating side of the preheater 07 and the heating side of the subcooler 05 are connected in series on the ambient temperature water replenishment pipeline, and the end of the water replenishment pipeline is unidirectionally connected to the first inlet of the flash tank 04. At the same time, the liquid water return port at the bottom of the flash tank 04 is connected to a pipe, which is connected to the heating side inlet of the condenser 03 via the circulating water pump 08; the heating side outlet of the condenser 03 is then connected back to the second inlet of the flash tank 04. Based on this architecture, ambient temperature water at around 20°C first enters the preheater 07 to absorb the waste heat of the heat source water, completing the first stage of heating; then it enters the subcooler 05 to absorb the high-grade sensible heat of condensation, completing the second stage of deep heating. After two stages of heating, the makeup water enters the flash evaporation tank 04 and is drawn by the circulating water pump 08 to the heating side of the condenser 03 for further heating. Then it returns to the flash evaporation tank 04 for instantaneous expansion and depressurization, and high-temperature pressurized saturated steam above 100°C is continuously output from the steam outlet at the top.

[0031] For the access of external heat source water, this system innovatively adopts a diversion and bypass micro-control architecture. The external heat source water pipeline flows sequentially through the heat release side of evaporator 01 and the heat release side of preheater 07. The external heat source water can be introduced into the system by a heat source water pump 09 located at the inlet end. It should be noted that, in this embodiment, the external heat source water can specifically be waste hot water generated at the industrial site, but it is not limited to this. Furthermore, the low-grade heat source of this invention is not limited to water sources, but can be replaced by other low-grade heat sources such as air sources, soil sources, industrial waste gas waste heat, and flue gas waste heat. By adjusting the heat exchange structure of the evaporator accordingly, it can be adapted to different heat source scenarios. In order to balance the cascade heat recovery effect and the water resistance of the system pipeline network, a diversion node is set between the heat release side outlet of evaporator 01 and the heat release side inlet of preheater 07, and a confluence node is set downstream of the heat release side outlet of preheater 07. After the initial heat exchange and cooling in evaporator 01, the entire volume of external heat source water is split into two streams upon reaching the diversion node: one stream flows into the heat release side of preheater 07 for further heat exchange and cooling; the other stream flows directly across preheater 07 via a bypass pipeline, ultimately merging with the heat source water that has passed through preheater 07 at the confluence node and flowing to the end. This bypass diversion arrangement avoids the significant water resistance and pump head loss caused by a large flow of heat source water forcibly entering preheater 07.

[0032] In a specific embodiment, by fully coupling the preheating of the makeup water stage with the deep subcooling on the refrigerant side, the system controls the subcooling of the refrigerant at the heat release side outlet of the subcooler 05 to be no less than 25°C. This deep subcooling of above 25°C greatly suppresses irreversible flash loss of the refrigerant during the subsequent throttling process. Simultaneously, the temperature difference between the makeup water that finally enters the flash evaporation tank 04 after two stages of heating and the temperature of the saturated water inside the flash evaporation tank 04 is controlled within a range not exceeding 20°C. This temperature difference control effectively reduces the drastic temperature fluctuations inside the tank and the irreversible flash loss caused by low-temperature makeup water, enabling a significant improvement in the overall energy utilization rate of the system under wide-range high-temperature condensation conditions.

[0033] It should be noted that the cascade heat recovery described in this application refers to a heat recovery method that captures and utilizes waste heat of different grades in order from low to high based on the gradient difference in heat quality, thereby realizing the cascade heating and resource utilization of the heat sink; the deep subcooling refers to the process in which the refrigerant is condensed into a saturated liquid state in the condenser and then further cooled by heat exchange to make the refrigerant temperature lower than the saturation temperature at the corresponding pressure.

[0034] In a specific embodiment, the compressor 02 in this system can be selected from one of the following: screw compressor, centrifugal compressor, scroll compressor, and reciprocating compressor, depending on the user's load requirements. It should be noted that the compressor 02 is not limited to a single unit; it can be multiple compressors 02 connected in parallel or multiple compressors 02 connected in series for multi-stage compression.

[0035] In specific embodiments, heat exchange devices such as condenser 03, evaporator 01, subcooler 05, and preheater 07 can be selected as plate-and-shell, shell-and-tube, plate, or coaxial heat exchangers according to operating requirements. Optionally, multiple preheaters 07 and / or subcoolers 05 can be configured, and these multiple heat exchangers can be connected in series via physical piping to expand the heat recovery levels. Optionally, condenser 03 and evaporator 01 are not limited to a single unit; they can be multiple units connected in series or in parallel to output water at different temperatures.

[0036] It should be noted that the present invention can add conventional energy efficiency improvement methods such as economizers, regenerators, and oil coolers to the high-temperature steam heat pump system, which will not be elaborated here.

[0037] In a specific embodiment, this application also proposes a cascade heat recovery method based on the above-mentioned high-temperature steam heat pump system, which specifically includes the following steps: Driven by compressor 02, the refrigerant circulates in the refrigerant circuit, condenses and releases high-grade heat in condenser 03, and further releases sensible heat in subcooler 05 to form deep subcooling. Room-temperature makeup water flows sequentially through preheater and subcooler 05 in the makeup water stage preheating circuit. In preheater 07, it absorbs heat from external heat source water to achieve a first temperature increase, and then in subcooler 05, it absorbs the sensible heat from the refrigerant subcooling to achieve a second temperature increase. After completing these two stages of temperature increases, the makeup water enters flash evaporation tank 04 and is drawn into the high-temperature heating cycle circuit. After absorbing the high-grade heat in condenser 03, it returns to the flash evaporation tank. The high-temperature water returning to flash evaporation tank 04 undergoes space expansion and pressure reduction, flashes into high-temperature saturated steam, and is discharged. This application couples deep refrigerant subcooling with makeup water stage preheating, recovering released heat to the heating cycle, achieving full resource utilization of the system's waste heat.

[0038] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A cascade heat recovery type high-temperature steam heat pump system, characterized in that, include: The refrigerant circuit includes a compressor, the heat-dissipating side of the condenser, the heat-dissipating side of the subcooler, a throttling device, and an evaporator that are connected in sequence. The water supply cascade preheating circuit includes a water supply pipeline, and a preheater and a subcooler connected in series on the water supply pipeline on the heated side; the end of the water supply pipeline is connected to the first water inlet of the flash tank. A high-temperature heating circulation loop includes the flash evaporation tank, a circulating water pump, and the heated side of the condenser; the liquid water return port of the flash evaporation tank is connected to the heated side inlet of the condenser via the circulating water pump, and the heated side outlet of the condenser is connected to the second inlet of the flash evaporation tank; wherein the top of the flash evaporation tank has a steam exhaust port; The ambient temperature water is heated by the water supply stage preheating circuit and then enters the flash evaporation tank. After being further heated by the condenser in the high temperature heating cycle circuit, steam is generated in the flash evaporation tank.

2. The heat pump system according to claim 1, characterized in that, It also includes a heat source water pipeline, which flows sequentially through the heat release side of the evaporator and the heat release side of the preheater; external heat source water is introduced from the inlet end of the heat source water pipeline, undergoes initial heat exchange and cooling on the heat release side of the evaporator, and then enters the heat release side of the preheater along the heat source water pipeline to release heat, so as to preheat the room temperature makeup water in the makeup water pipeline.

3. The heat pump system according to claim 2, characterized in that, The heat source water pipeline has a diversion node between the heat release side outlet of the evaporator and the heat release side inlet of the preheater, and a confluence node is provided downstream of the heat release side outlet of the preheater; the external heat source water, after being cooled by the evaporator, is divided into two paths at the diversion node, one part of which enters the heat release side of the preheater for heat exchange and cooling again, and then merges with the other part of the external heat source water that did not enter the preheater at the confluence node and is discharged.

4. The heat pump system according to claim 1, characterized in that, The temperature of the makeup water entering the flash evaporation tank after being heated by the preheater and the subcooler is no more than 20°C different from the temperature of the saturated water in the flash evaporation tank.

5. The heat pump system according to claim 1, characterized in that, The refrigerant in the refrigerant circuit has a subcooling degree of not less than 25°C at the heat release side outlet of the subcooler.

6. The heat pump system according to any one of claims 1 to 5, characterized in that, The system includes at least two stages of the preheater and / or at least two stages of the subcooler arranged in series.

7. The heat pump system according to claim 1, characterized in that, The throttling device is selected from one of the following: electronic expansion valve, thermostatic expansion valve, capillary tube, and orifice plate throttling mechanism.

8. The heat pump system according to claim 1, characterized in that, The condenser, the evaporator, the subcooler, and the preheater are one of the following: plate heat exchanger, shell-and-tube heat exchanger, plate heat exchanger, and coaxial heat exchanger.

9. The heat pump system according to claim 1, characterized in that, The compressor is one of the following: screw compressor, centrifugal compressor, scroll compressor, and reciprocating compressor.

10. A cascade heat recovery method based on the high-temperature steam heat pump system according to any one of claims 1 to 9, characterized in that, Includes the following steps: Driven by the compressor, the refrigerant circulates in the refrigerant circuit, condenses and releases high-grade heat in the condenser, and further releases sensible heat in the subcooler to form deep subcooling; In the water replenishment stage preheating circuit, the ambient temperature water flows through the preheater and the subcooler in sequence. In the preheater, it absorbs heat from the external heat source water to obtain a first temperature rise, and then absorbs the sensible heat from the subcooling of the refrigerant to obtain a second temperature rise. After completing the two-stage heating process, the replenished water enters the flash evaporation tank and is drawn into the high-temperature heating circulation loop. After absorbing the high-grade heat in the condenser, it returns to the flash evaporation tank. The high-temperature water returned to the flash evaporation tank flashes to generate steam and is then discharged.

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