Absorption type refrigerating, humidifying and dehumidifying seawater desalination system driven by solar heat

Abstract

The utility model discloses a solar heat-driven absorption type refrigerating, humidifying and dehumidifying seawater desalination system, which comprises a seawater flowing system, an air circulating system, an absorption type refrigerating circulating system and a solar heat collection circulating system. The fresh water preparation device has the beneficial effects that (1) circulating air is used as a carrier of water, fresh water is prepared by humidifying and dehumidifying the air through seawater or brackish water, the water quality is safe, the operation is safe and reliable, and the fresh water preparation device is suitable for small-scale fresh water preparation; and (2) the solar absorption refrigeration technology and the humidifying and dehumidifying seawater desalination technology are coupled, so that the dependence on energy is low, the system flexibility is high, and the distributed and miniaturized development of the seawater desalination system is facilitated. And (3) the cooling capacity and the heat of the evaporator, the condenser and the absorber of the absorption refrigeration cycle system can be effectively utilized in the seawater flowing and air circulation system, so that the water yield and the water production ratio of the system are improved, and the seawater desalination efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of seawater desalination, in particular to an absorption refrigeration humidification-dehumidification seawater desalination system driven by solar heat. Background Technique

[0002] Conventional thermal seawater desalination technologies, such as multi-stage flash distillation, low-temperature multi-effect distillation, etc., are all suitable for large and medium-scale fresh water supply, and are insufficiently applicable to small-scale water use units: ① Seawater desalination requires a large amount of energy, and usually needs to be located near large chemical plants or power plants with relatively rich electricity, steam or waste heat resources; ② The construction, maintenance and operation of large seawater desalination systems all require a large amount of manpower and material resources, with high investment costs, complex systems, and cumbersome operation and maintenance processes, making it difficult to be applicable to small and decentralized water use units.

[0003] Therefore, the humidification-dehumidification seawater desalination system can stand out in the small-scale application of seawater desalination, and it has the characteristics of simple structure, flexible scale, low operating conditions, etc. At present, there is a humidification-dehumidification seawater desalination scheme with a vapor compression refrigeration cycle as Figure 1 shown, including an evaporator a1, a compressor a2, a condenser a3, a throttle valve a4, a pre-cooler a5, a seawater pump a6, a humidifier a7, a seawater spray pump a8, and a circulation fan a9. This system couples the vapor compression refrigeration cycle with the humidification-dehumidification seawater desalination process, and uses the vapor compression refrigeration cycle to provide heat and cold for the humidification-dehumidification seawater desalination process to realize the process of producing fresh water. The humidification-dehumidification seawater desalination scheme with a vapor compression refrigeration cycle requires electricity to produce fresh water. On the one hand, it does not meet the requirements of energy conservation and emission reduction under the "dual carbon" situation, and on the other hand, it is difficult to be applicable to application scenarios with insufficient power supply, such as remote islands, ocean-going ships and other scenarios. Content of the Utility Model

[0004] The purpose of the utility model is to overcome the above technical defects and propose an absorption refrigeration humidification-dehumidification seawater desalination system driven by solar heat, which applies the advantages of the humidification-dehumidification principle and solar absorption refrigeration technology to the seawater desalination system to improve the applicability of the seawater desalination system to small and decentralized water use units with limited resource and energy conditions.

[0005] The technical solution adopted by the utility model to achieve its technical purpose is: an absorption refrigeration humidification-dehumidification seawater desalination system driven by solar heat, including a seawater flow system, an air circulation system, and also including an absorption refrigeration cycle system and a solar heat collection cycle system.

[0006] The absorption refrigeration cycle system includes an absorber. One side of the absorber is connected to an evaporator, and the other side is connected to a solution throttle valve. A solution pump is further provided below the absorber. Both the solution pump and the solution throttle valve are connected to a solution heat exchanger. A generator is connected above the solution heat exchanger. The generator is connected to a condenser, and the condenser is connected to the evaporator through a refrigerant throttle valve.

[0007] The solar heat collection cycle system includes a solar collector and a heat preservation water tank. A first heat carrier pump and a valve are connected between the solar collector and the heat preservation water tank. An electric heater is further provided on the heat preservation water tank. The heat preservation water tank is connected to the generator through a second heat carrier pump and a valve.

[0008] The air circulation system includes a circulation fan. The circulation fan is connected to a humidifier, the humidifier is connected to a pre-cooler, and the pre-cooler is connected to the evaporator.

[0009] The seawater flow system includes a seawater pump. The seawater pump is connected to the pre-cooler, the pre-cooler is connected to the condenser, the condenser is connected to the humidifier, and the humidifier is connected to a seawater spray pump.

[0010] Preferably, the absorption refrigeration cycle system is coupled with the solar heat collection cycle system through the generator.

[0011] Preferably, the absorption refrigeration cycle system is coupled with the seawater flow system through the condenser and the absorber, and the absorption refrigeration cycle system is coupled with the air circulation system through the evaporator.

[0012] Preferably, the air circulation system is coupled with the seawater flow system through the pre-cooler and the humidifier.

[0013] The beneficial effects of the present utility model are as follows:

[0014] (1) The humidification and dehumidification seawater desalination principle adopted by the present utility model uses circulating air as the carrier of water, and desalinates fresh water by humidifying and dehumidifying the air with seawater or brackish water. The produced fresh water has safe quality, does not require pressurization and vacuum equipment, is safe and reliable in operation, and is suitable for small-scale fresh water production.

[0015] (2) The present utility model also adopts the coupling of solar absorption refrigeration technology and humidification and dehumidification seawater desalination technology. The solar absorption refrigeration technology provides the required heat and cold for the humidification and dehumidification of the air circulation system. The system hardly requires electric energy and has a low dependence on energy. Therefore, the system has high flexibility and is conducive to the distributed and miniaturized development of the seawater desalination system.

[0016] (3) The cooling capacity and heat of the evaporator, condenser, and absorber in the absorption refrigeration cycle system can all be effectively utilized in the seawater circulation and air circulation systems of the humidification-dehumidification seawater desalination system. Compared with the conventional thermal seawater desalination system, the present utility model can improve the solar energy utilization rate, increase the water production and water production ratio of the system, thereby improving the seawater desalination efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the schematic diagram of the humidification-dehumidification seawater desalination scheme for the vapor compression refrigeration cycle;

[0018] Figure 2 is the schematic diagram of the absorption refrigeration humidification-dehumidification seawater desalination system driven by solar heat of the present utility model.

[0019] In the figure, the markings are: evaporator a1, compressor a2, condenser a3, throttle valve a4, precooler a5, seawater pump a6, humidifier a7, seawater spray pump a8, circulation fan a9;

[0020] 1. Absorber; 2. Solution pump; 3. Solution heat exchanger; 4. Generator; 5. Solution throttle valve; 6. Condenser; 7. Refrigerant throttle valve; 8. Evaporator; 9. Precooler; 10. First heat carrier pump; 11. Solar collector; 12. Valve; 13. Insulated water tank; 14. Second heat carrier pump;

[0021] 15. Electric heater; 16. Seawater pump; 17. Humidifier; 18. Seawater spray pump; 19. Circulation fan. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present utility model will be further described below in conjunction with the embodiments of the drawings.

[0023] Embodiment 1

[0024] As Figure 2 shown: A solar heat-driven absorption refrigeration humidification-dehumidification seawater desalination system includes a seawater flow system, an air circulation system, and also includes an absorption refrigeration cycle system and a solar heat collection cycle system.

[0025] The absorption refrigeration cycle system includes an absorber 1. One side of the absorber 1 is connected to an evaporator 8, and the other side is connected to a solution throttle valve 5. A solution pump 2 is further provided below the absorber 1. Both the solution pump 2 and the solution throttle valve 5 are connected to a solution heat exchanger 3. A generator 4 is connected above the solution heat exchanger 3. The generator 4 is connected to a condenser 6, and the condenser 6 is connected to the evaporator 8 through a refrigerant throttle valve 7.

[0026] The solar heat collection and circulation system includes a solar collector 11 and a heat preservation water tank 13. A first heat carrier pump 10 and a valve 12 are connected between the solar collector 11 and the heat preservation water tank 13. An electric heater 15 is also provided on the heat preservation water tank 13. The heat preservation water tank 13 is connected to the generator 4 through a second heat carrier pump 14 and a valve 12.

[0027] The air circulation system includes a circulation fan 19. The circulation fan 19 is connected to a humidifier 17. The humidifier 17 is connected to a pre-cooler 9. The pre-cooler 9 is connected to an evaporator 8.

[0028] The seawater flow system includes a seawater pump 16. The seawater pump 16 is connected to the pre-cooler 9. The pre-cooler 9 is connected to a condenser 6. The condenser 6 is connected to the humidifier 17. The humidifier 17 is connected to a seawater spray pump 18.

[0029] The absorption refrigeration cycle system is coupled with the solar heat collection and circulation system through the generator 4.

[0030] The absorption refrigeration cycle system is coupled with the seawater flow system through the condenser 6 and the absorber 1. The absorption refrigeration cycle system is coupled with the air circulation system through the evaporator 8.

[0031] The air circulation system is coupled with the seawater flow system through the pre-cooler 9 and the humidifier 17.

[0032] The operation process of the present utility model is as follows: The system follows the principles of the absorption refrigeration cycle system and humidification and dehumidification seawater desalination. The driving energy form is solar heat and a small amount of pump work. Its working process is divided into four parts: the absorption refrigeration cycle system, the solar heat collection and circulation system, the air circulation system, and the seawater flow system.

[0033] I. Absorption refrigeration cycle system: The absorption refrigeration cycle system adopts water-lithium bromide (H 2(O—LiBr) is used as the refrigerant-absorbent working pair. In the absorber 1, the refrigerant from the evaporative dehumidifier 8 is absorbed by the refrigerant-absorbent solution from the solution throttle valve 5. A large amount of absorption heat is released during this process. The absorber 1 exchanges heat with the humidifier 17 to cool the absorber 1 and provide heat for the humidification process of the humidifier 17. After the solution in the absorber 1 absorbs the refrigerant and becomes a dilute solution, the dilute solution is pressurized by the solution pump 2 from the absorber 1, exchanges heat with the concentrated solution through the solution heat exchanger 3 and is heated up, and then enters the generator 4. The dilute solution is heated by the heat carrier working fluid from the solar heat collection circulation system in the generator 4. After the dilute solution is heated and desorbed, the refrigerant volatilizes and becomes a two-phase state of high-temperature concentrated solution and high-temperature gaseous refrigerant. The gaseous refrigerant exits from the upper end of the generator 4, releases heat to the cold seawater in the seawater flow system through the condenser 6, and condenses into a liquid refrigerant. The liquid refrigerant is throttled and depressurized by the refrigerant throttle valve 7, cooled to a refrigerant gas-liquid mixture with cooling capacity, enters the evaporative dehumidifier 8, cools and dehumidifies the wet air. After the refrigerant vaporizes in the evaporative dehumidifier 8, it returns to the absorber 1 and is absorbed by the concentrated solution. On the other hand, the high-temperature concentrated solution exits from the lower end of the generator 4, exchanges heat with the dilute solution through the solution heat exchanger 3 and is cooled, and then passes through the throttling and depressurizing action of the solution throttle valve 5 and returns to the absorber 1 to absorb the gaseous refrigerant from the evaporative dehumidifier 8, thus starting the next cycle.

[0034] II. Solar heat collection circulation system: Driven by the first heat carrier working fluid pump 10 in the solar cycle, the heat carrier working fluid passes through the solar collector 11 from the heat preservation water tank 13. The solar energy is converted into heat energy for temperature rise. The high-temperature heat carrier working fluid returns to the heat preservation water tank 13. The high-temperature heat carrier working fluid then enters the generator 4 through the second heat carrier working fluid pump 14, heats and desorbs the solution in the generator 4, and then returns to the heat preservation water tank 13. If the temperature in the heat preservation water tank 13 is not sufficient to drive the desorption of the solution in the generator, the temperature of the heat carrier working fluid is raised by the electric heater 15 to reach the desorption temperature.

[0035] III. Air Circulation System: The process that air goes through is A1 → A2 → A3 → A1. Dried cold air A1, driven by the circulation fan 19, is blown into the lower air pipeline inlet of the humidifier 17, where it undergoes heat and mass exchange with the sprayed hot seawater. The air increases its enthalpy and humidity within the humidifier 17 and flows out from the upper air pipeline outlet of the humidifier 17, becoming hot and humid air A2 with a relatively high temperature and humidity. The hot and humid air A2 undergoes two cooling processes. First, it enters through the air pipeline of the pre-cooler 9 and exchanges heat with seawater W1. The hot and humid air is cooled into humid air A3 within the pre-cooler 9. Secondly, the humid air A3 continues to enter the evaporative dehumidifier 8 to exchange heat with the refrigerant, and the humid air is further cooled. During these two cooling processes, the hot and humid air first releases part of its sensible heat, reducing its temperature to the dew point temperature, and then enters the process of cooling and dehumidification. After the cooling and dehumidification process ends, the condensed fresh water W flows out from the evaporative dehumidifier 8, and the dried cold air A1 is driven by the circulation fan 19 for the next cycle.

[0036] IV. Seawater Flow System: The seawater flow system undergoes the process of W1 → W2 → W3 → W4, as well as the humidifier cycle of W5. The feed seawater W1, driven by the seawater pump 16 in the seawater circulation, enters the pre-cooler 9. After exchanging heat with the hot and humid air A2, it is heated up to seawater W2, then enters the condenser 6 to exchange heat with the refrigerant and continues to be heated up to seawater W3. Then it enters the spraying end of the humidifier 17, mixes with the concentrated seawater W5, and is sprayed. It makes full contact with the dry air in the air circulation system. Part of the seawater vaporizes into water vapor, and the heat comes from the temperature of the seawater itself and the absorption heat of the absorber 1. After spraying, a part of the concentrated seawater W4 is discharged outside the system, and another part of the concentrated seawater W5 undergoes the humidifier cycle. It is mixed with the seawater of W3 through the seawater spraying pump and is sprayed again to make contact with the dry air.

[0037] For the refrigerant-absorbent working pairs in the absorption refrigeration cycle system, other working pairs can also be used, such as water-based working pairs: water-lithium chloride (H 2 O—LiCl), water-ionic liquid; ammonia-based working pairs: ammonia-lithium nitrate (NH 3 —LiNO 3 ), ammonia-sodium thiocyanate (NH 3 —NaSCN); Freon-based working pairs: HFCs—DMF (trimethylformamide); alkane refrigerant working pairs: R290-mineral oil.

[0038] The humidifier 17 can also adopt different forms of high-efficiency humidifiers, such as a packed humidifier, and can also adopt a multi-stage humidification form. The purpose is to increase the contact area between air and seawater and prolong the contact time, so as to improve the mass transfer efficiency of the humidifier and thus increase the relative humidity of air A2, and improve the energy utilization efficiency of the system.

Claims

1. A solar thermal driven absorption refrigeration humidification and dehumidification seawater desalination system, comprising a seawater flow system and an air circulation system, characterized in that: It also includes absorption refrigeration cycle system and solar heat collection cycle system. The absorption refrigeration cycle system comprises an absorber, one side of the absorber is connected to the evaporator, and the other side is connected to the solution throttle valve, a solution pump is also provided below the absorber, the solution pump and the solution throttle valve are both connected to a solution heat exchanger, a generator is connected above the solution heat exchanger, the generator is connected to a condenser, and the condenser is connected to the evaporator through a refrigerant throttle valve; The solar thermal collection circulation system comprises a solar thermal collector and an insulated water tank. A first heat-carrying medium pump and a valve are connected between the solar thermal collector and the insulated water tank. An electric heater is also provided on the insulated water tank. The insulated water tank is connected to the generator through a second heat-carrying medium pump and a valve. The air circulation system comprises a circulation fan, the circulation fan is connected to a humidifier, the humidifier is connected to a precooler, and the precooler is connected to an evaporator; The seawater flow system comprises a seawater pump, the seawater pump is connected to a precooler, the precooler is connected to a condenser, the condenser is connected to a humidifier, and the humidifier is connected to a seawater spray pump.

2. The solar thermal driven absorption refrigeration humidification and dehumidification seawater desalination system according to claim 1 is characterized in that: The absorption refrigeration cycle system is coupled to the solar heat collection cycle system through a generator.

3. The solar thermal driven absorption refrigeration humidification and dehumidification seawater desalination system according to claim 1, characterized in that: The absorption refrigeration cycle system is coupled to the seawater flow system through a condenser and an absorber, and the absorption refrigeration cycle system is coupled to the air circulation system through an evaporator.

4. The solar thermal driven absorption refrigeration humidification and dehumidification seawater desalination system according to claim 1, characterized in that: The air circulation system is coupled to the seawater flow system through a precooler and a humidifier.

Images