A multi-stage flash seawater desalination device driven by a heat pump in stages

Abstract

The utility model relates to seawater desalination equipment technical field, concretely relates to a kind of multistage flash evaporation seawater desalination device of heat pump grading drive, including the main seawater pump of the seawater introduction device, still include the multistage independent operation heat pump system connected with main seawater pump, and the flash evaporation unit of one-to-one correspondence with heat pump system quantity identity, each set The heat pump system includes evaporator, compressor, condenser and expansion valve connected by pipeline and formed into refrigerant circuit, the evaporator is located in flash evaporation unit, still include the control system of controlling each stage heat pump system, flash evaporation unit, the energy precise matching and cascade utilization of the present application are realized: each stage heat pump system only needs to provide the moderate temperature rise and heat matched with corresponding flash evaporation temperature interval, avoid the energy quality waste problem of "high quality low use" existing in traditional single heat source system, greatly improve the thermodynamic perfection of system.

Description

Technical Field

[0001] This utility model relates to the technical field of seawater desalination equipment, specifically to a multi-stage flash seawater desalination device driven by a heat pump. Background Technology

[0002] With global population growth, industrial development, and the impact of climate change, freshwater scarcity has become a key issue restricting sustainable development in many regions. Seawater desalination, as an important means of obtaining a stable and reliable freshwater supply, has received increasing attention for its technological development and large-scale application. Currently, mainstream seawater desalination technologies mainly include thermal desalination, represented by multi-stage flash evaporation and multi-effect evaporation, and membrane desalination, represented by reverse osmosis. Although these technologies are relatively mature and widely used in practical engineering, they all suffer from excessive energy consumption during operation. Whether it's the large amount of heat and electricity required for thermal desalination or the high-pressure pumping energy required for membrane desalination, both contribute to high water production costs and bring significant carbon emissions and environmental pressure. Therefore, how to significantly reduce the energy consumption level of seawater desalination and develop efficient, low-carbon desalination technologies has become a key focus and challenge in this field of research. Utility Model Content

[0003] To address the problems existing in the prior art, this utility model provides a multi-stage flash seawater desalination device driven by a heat pump, which solves the problem of high energy consumption in existing seawater desalination equipment.

[0004] To solve the above problems, the technical solution of this utility model is as follows: A multi-stage flash seawater desalination device driven by a heat pump includes a main seawater pump that introduces seawater into the device, a multi-stage independently operating heat pump system connected to the main seawater pump, and flash units that are the same number as the heat pump systems and correspond one-to-one. Each heat pump system includes an evaporator, a compressor, a condenser, and an expansion valve connected by pipelines to form a refrigerant circuit. The evaporator is located in the flash unit. The device also includes a control system that controls the heat pump systems and flash units at each stage.

[0005] Furthermore, the heat pump system is three-stage, including a primary heat pump system, a secondary heat pump system, and a tertiary heat pump system.

[0006] Furthermore, the primary heat pump system includes a primary evaporator, a primary compressor, a primary condenser, and a primary expansion valve, with the primary evaporator located within the primary flash unit.

[0007] Furthermore, the secondary heat pump system includes a secondary evaporator, a secondary compressor, a secondary condenser, and a secondary expansion valve, with the secondary evaporator located within the secondary flash unit.

[0008] Furthermore, the three-stage heat pump system includes a three-stage evaporator, a three-stage compressor, a three-stage condenser, and a three-stage expansion valve, with the three-stage evaporator located within the three-stage flash unit.

[0009] Furthermore, the flash evaporation unit includes a primary flash evaporation chamber, a secondary flash evaporation chamber, and a tertiary flash evaporation chamber corresponding to the heat pump system, and is equipped with a primary spray head, a secondary spray head, and a tertiary spray head. The bottom of the tertiary flash evaporation chamber is equipped with a drain pipe.

[0010] Furthermore, the flash evaporation unit also includes: The inlet of the primary spray pump is connected to the outlet of the primary condenser, and the outlet is connected to the primary spray head in the primary flash chamber. The secondary spray pump has its inlet connected to the bottom of the primary flash chamber and its outlet connected to the secondary spray head inside the secondary flash chamber. The three-stage spray pump has its inlet connected to the bottom of the two-stage flash chamber and its outlet connected to the three-stage spray head inside the three-stage flash chamber.

[0011] Furthermore, a primary water collector, a secondary water collector, and a tertiary water collector are installed above the primary, secondary, and tertiary spray heads. The three water collectors are connected in sequence through pipelines to collect and output the fresh water.

[0012] Furthermore, the evaporator of each stage of the heat pump system is located above the seawater surface in the corresponding flash chamber. It is used to absorb the heat of the water vapor generated by flash evaporation and condense it into fresh water. At the same time, the refrigerant in the evaporator absorbs heat and evaporates before being drawn into the compressor to complete the heat pump cycle.

[0013] Furthermore, a demister is installed between the spray head and the water collector.

[0014] Compared with the prior art, the present invention has the following beneficial effects: I. Achieving precise energy matching and cascade utilization: By coupling multi-stage flash evaporation units with heat pump systems in a one-to-one correspondence, each stage of the heat pump system only needs to provide a moderate temperature rise and heat that matches its corresponding flash evaporation temperature range, completely avoiding the energy quality waste problem of "high quality but low use" that exists in traditional single heat source systems (i.e., high-temperature heat source used for low-temperature heating), and greatly improving the thermodynamic perfection of the system.

[0015] II. High-Efficiency Recovery of Latent and Sensible Heat: The core energy exchange of the device occurs on two levels: 1. In the flash chamber: The evaporator is positioned above the liquid surface, directly absorbing the large amount of latent heat released during the condensation of water vapor generated by the staged flash evaporation of seawater. This causes the refrigerant to evaporate, while the water vapor condenses into fresh water and is collected. This is a highly efficient heat pump evaporation-side heat absorption process. 2. In the condenser: The heat released during the condensation of the high-temperature, high-pressure refrigerant vapor from the compressor is not wasted but used to preheat the seawater flow that is about to enter the flash chamber. This design forms a highly integrated internal energy circulation network, which not only significantly reduces the system's operating energy consumption and carbon emission intensity but also improves the flexibility and adaptability of the device's operation, providing a new technological path for achieving low-energy, low-carbon seawater desalination.

[0016] 3. Modular design, easy to expand and maintain. Each heat pump system + flash unit has an independent structure and complete functions. When expanding the system, unit modules can be added directly without major changes to the overall architecture. At the same time, the maintenance of a single module does not affect the operation of other modules, reducing maintenance costs and downtime risks.

[0017] Fourth, the staged drive mode significantly reduces the temperature rise span (compression ratio) of each stage of the heat pump, avoiding the requirement for extreme high pressure ratio and ultra-high outlet temperature of the compressor. This greatly reduces the manufacturing difficulty, procurement cost and dependence on special materials of the compressor, while improving the operating reliability, lifespan and overall system stability of the compressor. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the present invention.

[0019] In the diagram: 1. Primary spray head; 2. Primary water collector; 3. Primary evaporator; 4. Primary compressor; 5. Primary condenser; 6. Primary expansion valve; 7. Secondary spray head; 8. Secondary water collector; 9. Secondary evaporator; 10. Secondary compressor; 11. Secondary condenser; 12. Secondary expansion valve; 13. Tertiary spray head; 14. Tertiary water collector; 15. Tertiary evaporator; 16. Tertiary compressor; 17. Tertiary condenser; 18. Tertiary expansion valve; 19. Primary spray pump; 20. Secondary spray pump; 21. Tertiary spray pump; 22. Main seawater pump; 23. Demister; 24. Drain pipe; 25. Primary flash chamber; 26. Secondary flash chamber; 27. Tertiary flash chamber. Detailed Implementation

[0020] like Figure 1 As shown, a multi-stage flash seawater desalination device driven by a heat pump is characterized by its core feature of corresponding three independently operating heat pump systems with three flash evaporation units to achieve cascaded energy utilization and efficient seawater desalination.

[0021] The device mainly includes: Main seawater pump 22: Responsible for introducing the seawater to be treated into the entire unit.

[0022] Three heat pump systems: Each system operates independently and includes an evaporator, compressor, condenser, and expansion valve.

[0023] Three flash evaporation units: corresponding to the heat pump system, including flash chamber, spray head, spray pump and water collector.

[0024] Control system: Used to coordinate and control the operating parameters of each stage of the heat pump system and flash unit.

[0025] The workflow is as follows, such as Figure 1 As shown in the figure, the arrows in the heat pump system indicate the refrigerant circuit, the arrows in the flash evaporation unit indicate the seawater flow direction, and the arrows in the water collector indicate the freshwater flow direction.

[0026] 1. System startup and initialization: Connect the power supply and start the control system.

[0027] Driven by the main seawater pump 22, ambient temperature seawater (e.g., 25°C) begins to flow into the system, passing through the tertiary condenser 17, the secondary condenser 11, and the primary condenser 5 in sequence. During this process, the seawater is gradually preheated.

[0028] The control system sequentially starts the third-level, second-level, and first-level heat pump systems.

[0029] 2. Establishment of heat pump circulation The first-stage compressor 4 starts, compressing the refrigerant into a high-temperature, high-pressure gas, which is then sent to the first-stage condenser 5. In the first-stage condenser 5, the refrigerant releases heat to the flowing seawater and condenses itself into a high-pressure liquid.

[0030] The high-pressure liquid refrigerant is throttled and depressurized by the first-stage expansion valve 6, becoming a low-temperature, low-pressure gas-liquid two-phase mixture, and then enters the first-stage evaporator 3 installed in the first-stage flash chamber 25.

[0031] In the first-stage evaporator 3, the low-temperature refrigerant absorbs the latent heat of condensation of the water vapor generated in the first-stage flash chamber 25, rapidly evaporating into low-temperature, low-pressure vapor, which is then drawn into the first-stage compressor 4, completing one cycle. The first-stage evaporator 3, first-stage compressor 4, first-stage condenser 5, and first-stage expansion valve 6 are connected by pipelines to form the first-stage refrigerant loop. The second-stage and third-stage heat pump cycles are similar.

[0032] 3. Flash evaporation and freshwater generation process: High-temperature seawater (e.g., above 70°C) heated by the first-stage condenser 5 is pumped into the first-stage flash chamber 25 by the first-stage spray pump 19 and sprayed through the first-stage spray 1.

[0033] Because the internal pressure of the first-stage flash chamber 25 is lower than the saturation pressure of seawater at that temperature, some seawater flashes rapidly into water vapor. As the water vapor rises, it comes into contact with the lower-temperature tube wall of the first-stage evaporator 3, condenses and releases latent heat (which is absorbed by the refrigerant), and at the same time, it condenses into fresh water droplets that fall down and are collected by the first-stage water collector 2.

[0034] Unevaporated concentrated seawater falls to the bottom of the primary flash chamber 25, where its temperature and pressure decrease. This seawater is then pumped by the secondary spray pump 20 into the secondary spray 7 of the secondary flash chamber 26 for spraying.

[0035] Inside the secondary flash chamber 26, the process repeats: secondary flash evaporation → steam condenses on the secondary evaporator 9 → fresh water is collected by the secondary water collector 8, and the secondary concentrated seawater is then pumped into the tertiary flash chamber 27 by the tertiary spray pump 21 for a third flash evaporation and condensation.

[0036] A demister 23 is installed between each level of spray head and the water collector. The demister 23 is an existing technology device, and its structure will not be described in detail. This component can effectively capture the tiny salt mist droplets entrained in the flash steam, prevent them from entering the freshwater product, and ensure the purity of the produced water.

[0037] Finally, the fresh water collected by the tertiary water collector 14 is combined with the fresh water from the first and second stages and output as product water. The concentrated brine at the bottom of the tertiary flash chamber 27 is discharged from the system through the drain pipe 24.

[0038] System tuning and optimization: The control system monitors the liquid level and temperature of each flash chamber in real time, as well as the power and exhaust temperature of the compressor. For example, if the liquid level in the first-stage flash chamber 25 is too high, the control system can appropriately increase the frequency of the first-stage spray pump 19 or increase the opening of the first-stage expansion valve 6 to enhance the cooling capacity, thereby increasing the flash rate of that stage. Through this independent and precise control, it can be ensured that the three-stage flash evaporation and the three-stage heat pump are always in a highly efficient and well-matched collaborative working state.

[0039] This application achieves cascaded recovery and utilization of latent heat of steam through the coupling of a three-stage heat pump and flash evaporation. The energy consumption is much lower than that of traditional technologies. Each stage of the system is relatively independent, and fluctuations in one stage have little impact on the whole. The system has high operational stability, and the modular design structure is clear, which facilitates manufacturing, installation, maintenance and future expansion and upgrades.

[0040] The above specific embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to examples, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A multi-stage flash seawater desalination device driven by a heat pump, comprising a main seawater pump (22) for introducing seawater into the device, characterized in that: It also includes a multi-stage independently operating heat pump system connected to the main seawater pump (22), and flash evaporation units that are the same number as the heat pump systems and correspond one-to-one. Each heat pump system includes an evaporator, a compressor, a condenser and an expansion valve that are connected by pipelines to form a refrigerant circuit. The evaporator is located in the flash evaporation unit. It also includes a control system that controls the heat pump systems and flash evaporation units at each stage.

2. The multi-stage flash seawater desalination device according to claim 1, characterized in that: The heat pump system is three-stage, including a primary heat pump system, a secondary heat pump system, and a tertiary heat pump system.

3. The multi-stage flash seawater desalination device according to claim 2, characterized in that: The primary heat pump system includes a primary evaporator (3), a primary compressor (4), a primary condenser (5), and a primary expansion valve (6). The primary evaporator (3) is located within the primary flash unit.

4. The multi-stage flash seawater desalination device according to claim 3, characterized in that: The secondary heat pump system includes a secondary evaporator (9), a secondary compressor (10), a secondary condenser (11), and a secondary expansion valve (12), with the secondary evaporator located within the secondary flash unit.

5. The multi-stage flash seawater desalination device according to claim 4, characterized in that: The three-stage heat pump system includes a three-stage evaporator (15), a three-stage compressor (16), a three-stage condenser (17), and a three-stage expansion valve (18), wherein the three-stage evaporator (15) is located within the three-stage flash unit.

6. The multi-stage flash seawater desalination device according to claim 5, characterized in that: The flash unit includes a primary flash chamber (25), a secondary flash chamber (26), and a tertiary flash chamber (27) corresponding to the heat pump system. Each chamber is equipped with a primary spray head (1), a secondary spray head (7), and a tertiary spray head (13). The bottom of the tertiary flash chamber (27) is equipped with a drain pipe (24).

7. The multi-stage flash seawater desalination device according to claim 6, characterized in that, The flash evaporation unit further includes: The inlet of the primary spray pump (19) is connected to the outlet of the primary condenser (5), and the outlet is connected to the primary spray head (1) in the primary flash chamber (25). The secondary spray pump (20) has its inlet connected to the bottom of the primary flash chamber (25) and its outlet connected to the secondary spray head (7) inside the secondary flash chamber (26); The three-stage spray pump (21) has its inlet connected to the bottom of the two-stage flash chamber (26) and its outlet connected to the three-stage spray head (13) inside the three-stage flash chamber (27).

8. The multi-stage flash seawater desalination device according to claim 7, characterized in that: Above the primary spray head (1), secondary spray head (7), and tertiary spray head (13) are provided a primary water collector (2), a secondary water collector (8), and a tertiary water collector (14). The three water collectors are connected in sequence through pipelines to collect fresh water and output it.

9. The multi-stage flash seawater desalination device according to claim 8, characterized in that: The evaporator of each stage of the heat pump system is located above the seawater surface of the corresponding flash chamber. It is used to absorb the heat of the water vapor generated by flash evaporation and condense it into fresh water. At the same time, the refrigerant in the evaporator absorbs heat and evaporates before being drawn into the compressor to complete the heat pump cycle.

10. The multi-stage flash seawater desalination device according to claim 9, characterized in that: A demister (23) is installed between the spray head and the water collector.

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