Cascade high-temperature heat pump driven low-carbon steam generation device and method

Abstract

The present invention discloses a cascade high-temperature heat pump driven low-carbon steam generating device and method, which relates to the technical field of steam generation, including a low-temperature heat pump, a high-temperature heat pump, a flash tank and a steam ejection device, wherein the low-temperature heat pump is used to extract a first heat from a low-temperature heat source, and the high-temperature heat pump is used to extract a second heat from the low-temperature heat pump and output high-temperature hot water to the flash tank, and the flash tank converts the high-temperature hot water into a gas-liquid two-phase mixture of saturated steam and saturated water by pressure reduction flash evaporation, and is separated into saturated steam and saturated water at a relatively low temperature and pressure, wherein the saturated water returns to the high-temperature heat pump to continue to be heated, and the saturated steam is compressed by a water vapor compressor and then enters the user end or enters the user end through the steam ejection device; the present invention can effectively reduce carbon dioxide emissions and reduce energy consumption.

Description

Technical Field

[0001] The invention relates to the technical field of steam generation, and in particular to a cascade high-temperature heat pump driven low-carbon steam generation device and method. Background Art

[0002] High-temperature steam is widely used in people's production and life. It can be used for food sterilization and cooking in agriculture; it can be used for disinfection and high-temperature carbonization tests in the biopharmaceutical industry, high-temperature heating in the packaging industry, etc. in industry; it can be used to produce gunpowder and explosives in the military; it can also be used for disinfection in hospitals, schools and chemical plants in life. At present, the supply of high-temperature steam mainly adopts oil, coal and gas boilers, which have problems such as "high pollution, high energy consumption and high emissions". With the changes in the energy supply structure and the continuous improvement of energy conservation and environmental protection requirements, the use of clean energy will be an inevitable trend in the future development of the high-temperature steam field.

[0003] At present, the air source high temperature heat pump steam boiler system is a hot topic in the field of industrial energy conservation. It can raise the low-grade heat source in the ambient air to the required steam temperature, realize the supply of saturated steam above 100°C, and continuously supply high temperature and high pressure steam in a low temperature environment of -20°C. As a new steam supply technology, the air source high temperature heat pump steam boiler system can replace traditional oil, coal, gas, and pure electric steam boilers, solve the problems of "high pollution, high energy consumption, and high emissions" in traditional boilers, and is the future development trend of the high temperature steam field.

[0004] However, conventional heat pumps are single-stage heat pumps, and due to the performance of the components and equipment themselves and working conditions, the water supply temperature generally does not exceed 60°C.

[0005] In addition, a steam ejector is required during the steam supply process. The steam ejector is a device that uses high-speed steam flow to introduce liquid or gas into the system. Its main advantages include:

[0006] 1. Energy saving: The steam ejector converts high-pressure steam into a high-speed steam flow, thereby generating negative pressure to eject liquid or gas. It does not require external energy and can save a lot of energy.

[0007] 2. No power: The steam ejector does not require an external power source. It can operate normally as long as steam is provided. There are no moving parts such as motors, reducers, gears, etc., so it operates stably and reliably and has a long service life.

[0008] 3. Low maintenance cost: Since the steam ejector does not require an additional drive device, there is no need for regular maintenance or replacement of moving parts, only regular cleaning and inspection.

[0009] 4. Strong material adaptability: Steam ejectors are usually made of corrosion-resistant materials and can maintain good operating conditions in different dust, corrosive gas and other environments.

[0010] However, there are some disadvantages, mainly: the steam jet device will generate a lot of noise and vibration. This will have a certain impact on the working environment and the health of the workers, and may cause hearing and neurological problems. In addition, noise and vibration will also have a negative impact on the machine itself, reducing its service life.

[0011] Therefore, it is necessary to provide a cascade high-temperature heat pump driven low-carbon steam generation device and method to solve the problems raised in the above background technology. Summary of the invention

[0012] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a cascade high-temperature heat pump drives a low-carbon steam generating device, comprising a low-temperature heat pump, a high-temperature heat pump, a flash tank and a steam ejection device, wherein the low-temperature heat pump is used to extract a first heat from a low-temperature heat source, and the high-temperature heat pump is used to extract a second heat from the low-temperature heat pump, and output high-temperature hot water to the flash tank, and the flash tank converts the high-temperature hot water into a gas-liquid two-phase mixture of saturated steam and saturated water by pressure reduction flash evaporation, and is separated into saturated steam and saturated water at a relatively low temperature and pressure, wherein the saturated water returns to the high-temperature heat pump to continue to be heated, and the saturated steam is compressed by a water vapor compressor and then enters the user end or enters the user end through the steam ejection device.

[0013] Further, as a preference, the low-temperature heat pump comprises a low-temperature evaporator, a low-temperature compressor, an internal heat exchange tube in a low-temperature condenser, and a low-temperature expansion valve which are sequentially connected end to end in series through a first pipeline.

[0014] Further, as a preference, the high-temperature heat pump comprises a high-temperature expansion valve, an outer shell in a low-temperature condenser, a high-temperature compressor, and an internal heat exchange tube in the high-temperature condenser, which are connected in series end to end through a second pipeline.

[0015] Further, as a preference, the flash tank is located on the third pipeline of the closed loop, and the third pipeline is sequentially connected in series with the flash tank, the circulating water pump, and the outer shell of the high-temperature condenser;

[0016] The flash tank is also connected to a water supply pipe, on which a water supply pump and a flow regulating valve are arranged.

[0017] Further, preferably, when saturated steam is compressed by a water vapor compressor and enters the user end, the water vapor compressor is also connected to a water supply pipe, and when saturated steam enters the user end through a steam ejection device, the steam ejection device is driven by external high-pressure steam.

[0018] Further, as a preference, the steam ejection device comprises a high-pressure steam pipe, a low-pressure steam pipe and an inner pipe, wherein one end of the high-pressure steam pipe is used to receive high-pressure steam, and the other end is connected to a nozzle, the outside of the nozzle is provided with a silent tube, the silent tube is embedded in the inner tube, the interior of the inner tube is formed with a pipeline portion, an expansion portion, a mixing portion and a guide portion from left to right, the guide portion is wrapped around the outside of the nozzle, the bottom of the silent tube is connected to a low-pressure steam pipe, and the low-pressure steam pipe is used to be connected to the exhaust end of the flash tank.

[0019] Furthermore, preferably, a noise reduction chamber is provided in the mixing section, and an energy absorbing column is connected to the noise reduction chamber by an energy absorbing spring.

[0020] Further, preferably, a plurality of magnetic strips are embedded in the mixing portion, the plurality of magnetic strips are distributed in a circle, and a spoiler column is provided at the central axis position of the circle, and the spoiler column is attracted and positioned by the magnetic strips.

[0021] Further, as a preference, the low-pressure steam pipe is connected to the exhaust end of the flash tank by a first venturi tube, the first venturi tube is connected to the inner tube by a fourth pipeline, a collecting ball is arranged on the fourth pipeline, gravel is pre-installed in the collecting ball, a blocking net is also embedded in the inner tube, the blocking net is located at the connection between the fourth pipeline and the inner tube and on the side away from the nozzle, and the blocking net is used to intercept gravel;

[0022] One end of the high-pressure steam pipe away from the nozzle is connected to a second venturi tube, and the second venturi tube is connected to the collecting ball through a fifth pipeline.

[0023] A cascade high-temperature heat pump driven low-carbon steam generation method comprises the following steps:

[0024] S1. Obtaining a first heat from a low-temperature heat source through a low-temperature heat pump;

[0025] S2. Obtaining a second heat from the low-temperature heat pump through the high-temperature heat pump and outputting high-temperature hot water to the flash tank;

[0026] S3. The flash tank converts high-temperature hot water into a gas-liquid two-phase mixture of saturated steam and saturated water by pressure reduction flash evaporation, and is separated into saturated steam and saturated water at relatively low temperature and pressure. The saturated water returns to the high-temperature heat pump to continue to be heated, and the saturated steam is compressed by the water vapor compressor and then enters the user end or enters the user end through the steam ejector.

[0027] Compared with the prior art, the present invention provides a cascade high-temperature heat pump driven low-carbon steam generation device and method, which has the following beneficial effects:

[0028] In the embodiment of the present invention, air energy is extracted from the air by a low-temperature heat pump and a high-temperature heat pump to heat water to above 90°C, and then sent to a flash tank to be flash evaporated to become a gas-liquid two-phase mixture of saturated steam and saturated water. At a relatively low temperature and pressure, the saturated steam is separated into saturated steam and saturated water. After being compressed by a water vapor compressor, the saturated steam is pressurized and heated to a high-temperature and high-pressure state, and finally supplied to users. The energy source of the technology is mainly air energy in the environmental heat source and a small amount of electrical energy. It has significant social and economic benefits, and can effectively reduce carbon dioxide emissions and energy consumption.

[0029] In the embodiment of the present invention, the configured silent pipe can wrap the inner pipe and the nozzle to play a noise reduction role, and can also prevent the low-pressure steam in the low-pressure steam pipe from directly impacting the guide part. Moreover, the low-pressure steam in the low-pressure steam pipe first enters the silent pipe and then is discharged from the inner pipe. During this period, the low-pressure steam can be fully guided to improve its flow stability. In addition, by configuring the spoiler column, the sound wave energy can be absorbed to a certain extent and the noise can be reduced. In addition, the spoiler column can also play a spoiler role, which can well suppress eddy currents and thus reduce noise. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of a low-carbon steam generator driven by a cascade high-temperature heat pump Figure 1 ;

[0031] Figure 2 Schematic diagram of the structure of a low-carbon steam generator driven by a cascade high-temperature heat pump Figure 2 ;

[0032] Figure 3 It is a schematic diagram of the structure of the steam ejector device in the low-carbon steam generating device driven by a cascade high-temperature heat pump;

[0033] Figure 4 for Figure 3 A partially enlarged structural schematic diagram;

[0034] In the figure: 1. low temperature heat pump; 2. high temperature heat pump; 3. flash tank; 4. steam ejector; 5. circulating water pump; 6. water vapor compressor; 7. make-up water pump; 8. flow regulating valve; 11. low temperature evaporator; 12. low temperature compressor; 13. low temperature condenser; 14. low temperature expansion valve; 21. high temperature expansion valve; 22. high temperature compressor; 23. high temperature condenser; 41. high pressure steam pipe; 42. nozzle; 43. silent pipe; 44. low pressure steam pipe; 45. first venturi tube; 46. inner tube; 47. expansion part; 48. mixing part; 49. guide part; 410. straightening block; 411. noise reduction chamber; 412. second venturi tube; 413. screen; 414. collecting ball; 415. spoiler column; 416. magnetic strip; 417. energy absorption column. Implementation

[0035] See also Figure 1 to Figure 4 In the embodiment of the present invention, a cascade high-temperature heat pump drives a low-carbon steam generating device, including a low-temperature heat pump 1, a high-temperature heat pump 2, a flash tank 3 and a steam ejector 4, wherein the low-temperature heat pump 1 is used to extract a first heat from a low-temperature heat source, wherein the low-temperature heat source includes: renewable energy such as an air source, a ground source, and a water source;

[0036] The high-temperature heat pump 2 is used to extract the second heat from the low-temperature heat pump 1 and output high-temperature hot water to the flash tank 3. The flash tank 3 converts the high-temperature hot water into a gas-liquid two-phase mixture of saturated steam and saturated water by pressure reduction flash evaporation, and is separated into saturated steam and saturated water at a relatively low temperature and pressure, wherein the saturated water returns to the high-temperature heat pump 2 to continue to be heated, and the saturated steam is compressed by the water vapor compressor 6 and then enters the user end, or enters the user end through the steam ejector 4.

[0037] In one embodiment, the cascade high-temperature heat pump drives a low-carbon steam generating device, extracts air energy from the air through the low-temperature heat pump 1 and the high-temperature heat pump 2 to heat water to above 90°C, and then sends it to the flash tank 3 to be converted into a gas-liquid two-phase mixture of saturated steam and saturated water through pressure reduction flash evaporation, and is separated into saturated steam and saturated water at relatively low temperature and pressure. The saturated steam is compressed by the water vapor compressor 6 and then pressurized and heated to become a high-temperature and high-pressure state, and is finally supplied to users. The energy source of the technology is mainly the air energy in the environmental heat source and a small amount of electrical energy.

[0038] In this embodiment, the low-temperature heat pump 1 includes a low-temperature evaporator 11, a low-temperature compressor 12, an internal heat exchange pipe in a low-temperature condenser 13, and a low-temperature expansion valve 14 which are connected in series end to end through a first pipeline.

[0039] In this embodiment, the high-temperature heat pump 2 includes a high-temperature expansion valve 21, an outer shell in the low-temperature condenser 13, a high-temperature compressor 22, and an internal heat exchange tube in the high-temperature condenser 23, which are connected in series end to end through a second pipeline.

[0040] As a preferred embodiment, the flash tank 3 is located on the third pipeline of the closed loop, and the third pipeline is connected in series with the flash tank 3, the circulating water pump 5, and the outer shell of the high-temperature condenser 23;

[0041] The flash tank 3 is also connected to a water supply pipe, on which a water supply pump 7 and a flow regulating valve 8 are provided.

[0042] When saturated steam is compressed by the water vapor compressor 6 and enters the user end, the water vapor compressor 6 is also connected to the water supply pipe. When saturated steam enters the user end through the steam ejection device 4, the steam ejection device 4 is driven by external high-pressure steam.

[0043] Among them, the steam injection device will generate a lot of noise and vibration. This will have a certain impact on the working environment and the health of the workers, and may cause hearing and neurological problems. In addition, noise and vibration will also have a negative impact on the machine itself and reduce its service life.

[0044] After research and analysis, the main reasons for the noise generated by the steam injection device are the following three aspects:

[0045] 1. Steam jet noise: In the steam ejector, steam is ejected through a narrow nozzle, generating a large amount of jet noise.

[0046] 2. Air vibration noise: At the nozzle outlet, the high-speed steam flow is affected by the resistance from the surrounding gas flow. This resistance increases with the increase of steam flow rate, generating strong air vibration noise.

[0047] 3. Mechanical noise: Steam ejectors require the flow of liquid or gas, and the turbulence and friction noise generated by these flows will also lead to the generation of mechanical noise.

[0048] In order to reduce the noise of the steam injection device, in this embodiment, the steam injection device 4 includes a high-pressure steam pipe 41, a low-pressure steam pipe 44 and an inner pipe 46, wherein one end of the high-pressure steam pipe 41 is used to receive high-pressure steam, and the other end is connected to a nozzle 42, and a silent pipe 43 is provided on the outside of the nozzle 42, and an inner pipe 46 is embedded in the silent pipe 43. In addition, the inside of the silent pipe 43 can be connected to the inner pipe 46 by a straightening block 410, and the inside of the inner pipe 46 is formed with a pipeline portion, an expansion portion 47, a mixing portion 48 and a guide portion 49 from left to right, and the guide portion 49 is wrapped around the outside of the nozzle 42, and the bottom of the silent pipe 43 is connected to a low-pressure steam pipe 44, and the low-pressure steam pipe 44 is used to communicate with the exhaust end of the flash tank 3.

[0049] Among them, the silent tube 43 should be configured to have a longer length. On the one hand, it can wrap the inner tube 46 and the nozzle 42 to play a noise reduction role. It can also prevent the low-pressure steam in the low-pressure steam pipe 44 from directly impacting the guide part 49. In addition, the low-pressure steam in the low-pressure steam pipe 44 first enters the silent tube 43 and then is discharged from the inner tube 46. During this period, the low-pressure steam can be fully guided to improve its flow stability.

[0050] As a preferred embodiment, a noise reduction chamber 411 is provided in the mixing section 48 , and an energy absorbing column 417 is connected to the noise reduction chamber 411 by an energy absorbing spring.

[0051] As a preferred embodiment, a plurality of magnetic strips 416 are embedded in the mixing portion 48, and the plurality of magnetic strips 416 are distributed in a circle, and a spoiler column 415 is provided at the central axis position of the circle, and the spoiler column 415 is attracted and positioned by the magnetic strips 416, thereby reducing the installation plate of the spoiler column 415 and reducing the impact surface of the airflow.

[0052] It needs to be explained that when high-pressure gas and low-pressure gas meet, due to the difference in temperature and pressure, the gas will be compressed and expanded, and airflow and vortex will be formed between them, which may generate noise. The size of the noise depends on factors such as the speed difference between the gases, the density and pressure of the gases. When the gas speed increases, the noise will also increase.

[0053] In addition, noise is generated when high-pressure gas hits the metal rod. When high-pressure gas is ejected and hits the metal rod, vibration is generated, which causes the movement and collision of gas molecules, thus generating sound. In addition, the flow and turbulence of the high-pressure gas beam also affect the sound. Therefore, when high-pressure gas hits the metal rod, noise is usually generated.

[0054] It is difficult to make a specific comparison between the noise generated by the high-pressure gas and the low-pressure gas and the noise generated by the high-pressure gas hitting the metal rod. This is because the size of the noise depends on many factors, such as the pressure, speed, temperature of the gas, and the hardness of the object it hits. In addition, when the gases collide with each other, complex flows and vortices are generated, which also affect the noise. Therefore, the size of the noise generated in the two cases may be different depending on other environmental variables.

[0055] In general, the noise generated by the meeting of high-pressure gas and low-pressure gas is greater than the noise generated by the high-pressure gas hitting the metal rod. This is because when high-pressure gas and low-pressure gas meet, the speed of gas molecules will change rapidly, generating a large amount of sound wave energy, thus generating a large noise; while when high-pressure gas hits the metal rod, part of the sound wave energy generated will be absorbed by the metal rod, resulting in less noise.

[0056] That is to say, in this embodiment, by configuring the spoiler column 415, the sound wave energy can be absorbed to a certain extent and the noise can be reduced. In addition, the spoiler column 415 can also play a role of a spoiler, which can effectively suppress the eddy current and thus reduce the noise.

[0057] In addition, it should be noted that long-term exposure to high temperature environment will affect the magnetic properties of the magnet and may cause it to fail. This is because high temperature will change the grain structure and magnetic domain arrangement inside the magnet, resulting in a decrease in the magnetic properties of the magnet. The specific degree of impact will be affected by many factors, such as the magnet material, the shape and size of the magnet, the temperature and time, etc. Therefore, in practical applications, high-temperature resistant magnetic materials can be selected or other measures can be taken to reduce the temperature of the magnet.

[0058] In this embodiment, the low-pressure steam pipe 44 is connected to the exhaust end of the flash tank 3 by using the first venturi tube 45, and the first venturi tube 45 is connected to the inner tube 46 by using the fourth pipeline, and a collecting ball 414 is arranged on the fourth pipeline, and gravel is pre-set in the collecting ball 414. A blocking net 413 is also embedded in the inner tube 46, and the blocking net 413 is located at the connection between the fourth pipeline and the inner tube 46 and away from the nozzle 42. The blocking net 413 is used to intercept gravel;

[0059] One end of the high-pressure steam pipe 41 away from the nozzle is connected to a second venturi tube 412 , and the second venturi tube 412 is connected to a collecting ball 414 via a fifth pipeline.

[0060] In fact, valve bodies are provided on both the fourth pipeline and the fifth pipeline. When the valve body on the fourth pipeline is opened, the gravel in the collecting ball 414 can enter the first venturi tube 45, and then enter the inner tube 46 along with the low-pressure steam, so as to clean the silent tube 43 and the inner tube 46.

[0061] When the valve body on the fifth pipeline is opened, the gravel in the collecting ball 414 can enter the second venturi tube 412, and then enter the inner tube 46 along with the high-pressure steam, thereby cleaning the high-pressure steam pipe 41 and the inner tube 46;

[0062] It should be noted that the valve body on the fourth pipeline and the valve body on the fifth pipeline should be opened at different times.

[0063] A cascade high-temperature heat pump driven low-carbon steam generation method comprises the following steps:

[0064] S1. Obtaining a first heat from a low-temperature heat source through a low-temperature heat pump 1;

[0065] S2. Obtaining a second heat from the low-temperature heat pump 1 through the high-temperature heat pump 2, and outputting high-temperature hot water to the flash tank 3;

[0066] S3. The flash tank 3 converts the high-temperature hot water into a gas-liquid two-phase mixture of saturated steam and saturated water by pressure reduction flash evaporation, and is separated into saturated steam and saturated water at a relatively low temperature and pressure, wherein the saturated water returns to the high-temperature heat pump 2 to continue to be heated, and the saturated steam is compressed by the water vapor compressor 6 and then enters the user end, or the saturated steam enters the user end through the steam ejector 4.

[0067] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A cascade high-temperature heat pump driven low-carbon steam generating device, characterized in that: It includes a low-temperature heat pump, a high-temperature heat pump, a flash tank and a steam ejection device, wherein the low-temperature heat pump is used to extract a first heat from a low-temperature heat source, and the high-temperature heat pump is used to extract a second heat from the low-temperature heat pump and output high-temperature hot water to the flash tank, and the flash tank converts the high-temperature hot water into a gas-liquid two-phase mixture of saturated steam and saturated water by reducing the pressure and flash evaporation, and is separated into saturated steam and saturated water at a relatively low temperature and pressure, wherein the saturated water returns to the high-temperature heat pump to continue to be heated, and the saturated steam is compressed by a water vapor compressor and then enters the user end or enters the user end through the steam ejection device; The steam ejection device comprises a high-pressure steam pipe, a low-pressure steam pipe and an inner pipe, wherein one end of the high-pressure steam pipe is used to receive high-pressure steam, and the other end is connected to a nozzle, the outer sleeve of the nozzle is provided with a silent pipe, the inner pipe is embedded in the silent pipe, and the inner part of the inner pipe is formed with a pipeline part, an expansion part, a mixing part and a guide part from left to right in sequence, the guide part is wrapped around the outer part of the nozzle, the bottom of the silent pipe is connected to a low-pressure steam pipe, and the low-pressure steam pipe is used to be connected to the exhaust end of the flash tank; A noise reduction chamber is provided in the mixing section, and an energy absorbing column is connected to the noise reduction chamber by an energy absorbing spring; A plurality of magnetic strips are embedded in the mixing part, the plurality of magnetic strips are distributed in a circle, and a spoiler column is arranged at the central axis position of the circle, and the spoiler column is attracted and positioned by the magnetic strips.

2. The cascade high-temperature heat pump driven low-carbon steam generating device according to claim 1, characterized in that: The low-temperature heat pump comprises a low-temperature evaporator, a low-temperature compressor, an internal heat exchange pipe in a low-temperature condenser, and a low-temperature expansion valve which are connected in series end to end through a first pipeline.

3. The cascade high-temperature heat pump driven low-carbon steam generating device according to claim 2, characterized in that: The high-temperature heat pump comprises a high-temperature expansion valve, an outer shell in a low-temperature condenser, a high-temperature compressor, and an internal heat exchange pipe in the high-temperature condenser, which are connected in series end to end through a second pipeline.

4. The cascade high-temperature heat pump driven low-carbon steam generating device according to claim 3, characterized in that: The flash tank is located on the third pipeline of the closed loop, and the third pipeline is connected in series with the flash tank, the circulating water pump, and the outer shell of the high-temperature condenser in sequence; the flash tank is also connected to a water supply pipe, and a water supply pump and a flow regulating valve are provided on the water supply pipe.

5. The cascade high-temperature heat pump driven low-carbon steam generating device according to claim 4, characterized in that: When saturated steam is compressed by a water vapor compressor and enters the user end, the water vapor compressor is also connected to a water supply pipe. When saturated steam enters the user end through a steam ejector, the steam ejector is driven by external high-pressure steam.

6. The cascade high-temperature heat pump driven low-carbon steam generating device according to claim 1, characterized in that: The low-pressure steam pipe is connected to the exhaust end of the flash tank by a first venturi tube, the first venturi tube is connected to the inner tube by a fourth pipeline, a collecting ball is arranged on the fourth pipeline, gravel is pre-installed in the collecting ball, a blocking net is also embedded in the inner tube, the blocking net is located at the connection between the fourth pipeline and the inner tube and on the side away from the nozzle, the blocking net is used to intercept gravel; the end of the high-pressure steam pipe away from the nozzle is connected to a second venturi tube, the second venturi tube is connected to the collecting ball by a fifth pipeline.

7. A method for generating low-carbon steam by driving a cascade high-temperature heat pump, which uses a cascade high-temperature heat pump driven low-carbon steam generating device as claimed in any one of claims 1 to 6, characterized in that: The steps include: S1. Obtaining a first heat from a low-temperature heat source through a low-temperature heat pump; S2. Obtaining a second heat from the low-temperature heat pump through the high-temperature heat pump and outputting high-temperature hot water to the flash tank; S3. The flash tank converts high-temperature hot water into a gas-liquid two-phase mixture of saturated steam and saturated water by pressure reduction flash evaporation, and is separated into saturated steam and saturated water at relatively low temperature and pressure. The saturated water returns to the high-temperature heat pump to continue to be heated, and the saturated steam is compressed by the water vapor compressor and then enters the user end or enters the user end through the steam ejector.

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