Temperature difference energy driven compressed air distillation seawater desalination system and seawater desalination method

Abstract

The invention discloses a temperature difference energy driven compressed air distillation seawater desalination system and a seawater desalination method. The temperature difference energy driven compressed air distillation seawater desalination system comprises a compressed air distillation seawater desalination module, the compressed air distillation seawater desalination module comprises an absorber, a generator, a condenser, a gas-liquid separator, a fresh water storage tank, a solution pump and a solution throttle valve; the solution pump is connected between the dilute solution outlet of the absorber and the dilute solution inlet of the generator; the condenser is connected between the water vapor outlet of the generator and the fresh water storage tank; the gas-liquid separator is connected between a fresh water outlet of the condenser and a water vapor inlet of the absorber; the solution throttling valve is connected between a concentrated solution outlet of the absorber and a concentrated solution inlet of the generator; deep cold seawater is introduced into the absorber; and surface warm seawater is introduced into the generator. According to the invention, a renewable energy refrigeration mode of taking energy on site and using sea energy for sea is provided for preparing fresh water of tropical islands, and the fresh water demand of islands is cleanly and efficiently met.

Description

Technical Field

[0001] The invention relates to the field of renewable energy seawater desalination, and in particular to a temperature difference energy driven compressed gas distillation seawater desalination system. Background Art

[0002] The development of marine resources and island communities faces a severe shortage of fresh water. With the advancement of island construction and marine economic activities in the South China Sea, the demand for fresh water resources for domestic use of military and civilians stationed on the islands, agricultural and fishery production, and post-disaster rescue is becoming increasingly urgent. Seawater desalination is a key solution. Although traditional technologies such as reverse osmosis and evaporative crystallization can produce fresh water, they rely on high-energy high-pressure pumps or steam systems, which are limited in application on remote islands with weak power grids. Therefore, using renewable energy to drive the seawater desalination system has become a more sustainable and preferred option.

[0003] Ocean temperature difference energy, with its stable and continuous characteristics, provides an ideal energy basis for thermal desalination. Compared with intermittent solar energy and wind energy, this energy can effectively support thermal cycle systems such as absorption refrigeration by continuously supplying energy through the stable temperature difference between the surface and deep seawater. By coupling auxiliary heat sources such as solar energy to increase the gradient of the thermocline, a multi-energy complementary system can be formed, which can significantly improve the efficiency of freshwater production while ensuring the stable operation of the system, and open up a new path for building a low-carbon freshwater supply system for islands.

[0004] In the temperature difference energy desalination technology, distillation and flash evaporation are the mainstream processes. Traditional distillation relies on high-temperature heating to vaporize water into steam, which is suitable for high-purity fresh water production, but has high energy consumption and low efficiency. Flash evaporation optimizes energy consumption through low-pressure and low-temperature vaporization, but its flash evaporation pressure is limited by the condensation temperature. When the heat source temperature is constant, the conventional single-stage flash evaporation device cannot break through the flash evaporation pressure threshold due to the temperature constraint of the condensation end, resulting in limited seawater vaporization. Further reducing the flash evaporation pressure can increase the yield. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a temperature difference energy driven compressed gas distillation seawater desalination system and seawater desalination method that can reduce flash evaporation pressure and improve yield, thereby realizing ocean temperature difference energy driven seawater desalination.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A temperature difference energy driven compressed air distillation seawater desalination system, comprising a compressed air distillation seawater desalination module, the compressed air distillation seawater desalination module comprising an absorber, a generator, a condenser, a gas-liquid separator, a fresh water storage tank, a solution pump and a solution throttle valve; the absorber comprises a cold source inlet, a cold source outlet, a water vapor inlet, a concentrated solution inlet and a dilute solution outlet; the generator comprises a heat source inlet, a heat source outlet, a water vapor outlet, a dilute solution inlet and a concentrated solution outlet; the solution pump is connected between the dilute solution outlet of the absorber and the dilute solution inlet of the generator; the condenser is connected between the water vapor outlet of the generator and the fresh water storage tank; the gas-liquid separator is connected between the fresh water outlet of the condenser and the water vapor inlet of the absorber; the solution throttle valve is connected between the concentrated solution outlet of the absorber and the concentrated solution inlet of the generator; deep cold seawater is introduced into the cold source inlet of the absorber; surface warm seawater is introduced into the heat source inlet of the generator;

[0008] The low-pressure water vapor introduced from the water vapor inlet of the absorber is absorbed by the concentrated solution in the absorber to form a dilute solution. The heat released during the absorption process is taken away by the deep cold seawater. Subsequently, the dilute solution enters the generator under the action of the solution pump to exchange heat with the surface warm seawater to form a two-phase mixture consisting of a concentrated solution and high-pressure water vapor. The concentrated solution is reduced in pressure by a throttle valve and then enters the absorber to circulate and absorb the low-pressure water vapor. The high-pressure water vapor enters the condenser and is condensed into fresh water.

[0009] A low-pressure compressor for reducing the flash pressure is arranged between the gas-liquid separator and the water vapor inlet of the absorber.

[0010] A high-pressure compressor is arranged between the generator and the condenser for increasing the heat load of the condenser.

[0011] The temperature difference energy driven compressed gas distillation seawater desalination system also includes a cold seawater delivery module for delivering cold seawater.

[0012] The cold seawater transport module includes a transport pipe and a water reservoir, wherein the transport pipe connects the deep cold seawater and the water reservoir; the deep cold seawater naturally flows into the water reservoir from below the sea level along the deep cold seawater transport pipe due to the pressure difference H1 between the sea level and the liquid level of the water reservoir.

[0013] The temperature difference energy driven compressed gas distillation seawater desalination system also includes a solar thermal utilization module for providing warm seawater.

[0014] The solar thermal utilization module comprises a solar pool and a surface warm seawater pump; the solar pool is connected between the surface warm seawater pump and the heat source inlet of the generator.

[0015] By introducing surface warm seawater into the solar pool for heat storage, a salt solution concentration gradient is formed in the solar pool. As the density of the salt water increases with the salt content, the concentrated brine at the bottom absorbs solar energy and its temperature rises, achieving the effect of storing solar energy.

[0016] The solution circulating between the absorber and the generator is a concentrated lithium bromide solution.

[0017] A seawater desalination method based on the temperature difference energy driven compressed gas distillation seawater desalination device, comprising:

[0018] The deep cold seawater enters the generator from the first state S1 and is heated isobarically to the second state S2;

[0019] The seawater in the second state S2 passes through the diverter to the fourth state S4;

[0020] The seawater in the fourth state S4 is cooled and decompressed by the condenser 1 to the sixth state S6;

[0021] The seawater in the sixth state S6 enters the gas-liquid separator and is separated into low-pressure water vapor in the seventh state S7;

[0022] The low-pressure water vapor in the seventh state S7 is mixed with the lithium bromide concentrated solution in the twelfth state S12 to form a lithium bromide dilute solution in the eighth state S8;

[0023] The dilute lithium bromide solution in the eighth state S8 is heated and pressurized by a solution pump to become a dilute lithium bromide solution in the ninth state S9;

[0024] The dilute lithium bromide solution in the ninth state S9 is heated in the absorber to obtain a concentrated lithium bromide solution in the eleventh state S11 and high-pressure water vapor in the tenth state S10;

[0025] The lithium bromide concentrated solution in the 11th state is throttled to the lithium bromide concentrated solution in the 12th state S12 through the solution throttle valve;

[0026] The high-pressure steam in the 10th state S10 is condensed by the condenser to obtain fresh water in the 16th state.

[0027] The temperature difference energy driven compressed gas distillation seawater desalination system of the present invention comprises a compressed gas distillation seawater desalination module. The temperature difference energy driven compressed gas distillation seawater desalination system couples ocean temperature difference energy and solar thermal energy to drive a mixed working fluid absorption-generation process to realize a compressed gas distillation seawater desalination process. The compressed gas distillation seawater desalination module adopts an absorption-type compressed gas distillation desalination cycle, and realizes a lower evaporation temperature than traditional distillation through a low-boiling point absorbent solution, thereby reducing the demand for heat source grade. The evaporation and condensation processes are decoupled through an absorber and a generator, breaking through the restriction of the condensation end temperature of a conventional single-stage flash evaporation device on the flash evaporation pressure, and can further reduce the flash evaporation pressure to improve the yield.

[0028] The compressed gas distillation seawater desalination module includes but is not limited to the use of the absorption compressed gas distillation desalination cycle, and can also use an absorption compressed gas distillation desalination cycle assisted by low-pressure compression. By coupling low-pressure compression assistance on the basis of the absorption compressed gas distillation desalination cycle, the flash pressure is further reduced and the fresh water yield is improved. The low-pressure compression-assisted absorption compressed gas distillation desalination cycle is based on the absorption compressed gas distillation desalination cycle, and an additional compressor is added. The compressor is installed between the flash desalination device and the absorber to increase the pressure difference between the system flash pressure and the condensation pressure, thereby improving the fresh water yield.

[0029] The compressed gas distillation seawater desalination module includes but is not limited to the use of the absorption compressed gas distillation desalination cycle, and can also use an absorption compressed gas distillation desalination cycle assisted by high-pressure compression, that is, an additional compressor is added and installed between the generator and the condenser to increase the heat of the cold seawater at the condenser outlet, thereby improving the fresh water yield.

[0030] The cold seawater transport module uses the natural pressure difference to save transportation energy when the cold seawater is transported from the deep layer (about 1000 meters) to the nearshore reservoir. The natural pressure difference refers to the pressure difference caused by the height difference between the sea level and the liquid level of the reservoir, which allows the cold seawater to flow naturally along the pipeline into the reservoir, avoiding the energy required to lift the seawater from the seabed. In the process of cold seawater from the reservoir to the condenser, the vacuum pressure difference is used to save transportation energy. The vacuum pressure difference refers to the pressure in the condenser is close to zero, and the reservoir at the generator outlet is open and is affected by atmospheric pressure, and there is a pressure difference of about one atmosphere between the two. Since liquids always tend to flow from high-pressure areas to low-pressure areas, the cold seawater at one end of the reservoir can be naturally lifted by the pressure difference and enter the condenser, and the cold seawater at the condenser outlet flows out under the action of gravity, completing the cold seawater transportation. In this process, the pump only needs to overcome the flow resistance in the pipe, avoiding the pressurization process required to discharge the cold seawater from the condenser, saving transportation energy.

[0031] The solar thermal utilization module mainly includes a solar pool. A solar pool is a device that uses a salt solution concentration gradient to collect and store solar energy. By introducing surface warm seawater into the solar pool for heat storage, a salt solution concentration gradient is formed in the solar pool. As the density of the salt water increases with the salt content, the concentrated salt water at the bottom absorbs solar energy and its temperature rises, achieving the effect of storing solar energy, thereby increasing the heat exchange temperature of the generator and improving the operating efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the temperature difference energy driven compressed gas distillation seawater desalination system of the present invention;

[0033] Figure 2 Schematic diagram of the low-pressure compression-assisted temperature difference energy-driven compressed gas distillation seawater desalination system of the present invention;

[0034] Figure 3 Schematic diagram of the high-pressure compression-assisted temperature difference energy-driven compressed gas distillation seawater desalination system of the present invention;

[0035] Figure 4 Diagram of natural pressure rise of deep cold seawater;

[0036] Figure 5 Diagram of vacuum pressure rise of deep cold seawater;

[0037] Figure 6 Temperature difference can drive compressed gas distillation desalination system PT diagram;

[0038] Among them: 101-absorber; 102-generator; 103-condenser; 104-gas-liquid separator; 105-fresh water storage tank; 106-diverter; 107-condenser inlet throttle valve; 108-solution pump; 109-solution throttle valve; 110-solar pool; 111-surface warm seawater pump; 112-surface warm seawater; 113-deep cold seawater; 114-low-pressure compressor; 115-high-pressure compressor; 401-deep cold seawater transport pipe; 402-reservoir; 403-sea level; 501-overcoming resistance pump; H1-height difference between sea level and reservoir; H2-lifting height;

[0039] S1-S16 represent the 1st to 16th states respectively, among which, the 1st, 2nd and 4th states have the same pressure, and the 2nd and 4th states have the same pressure and temperature; the 6th, 7th, 8th and 12th states have the same pressure, and the 6th and 7th states have the same pressure and temperature; the 9th, 10th, 11th and 16th states have the same pressure, and the 10th and 11th states have the same pressure and temperature; the 14th and 15th states have the same pressure. DETAILED DESCRIPTION

[0040] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0041] Figure 1 A temperature difference energy driven compressed gas distillation desalination system suitable for preparing fresh water on tropical islands was demonstrated, including a compressed gas distillation desalination module driven by ocean thermal energy formed by the temperature difference between surface warm seawater and deep cold seawater and a solar thermal utilization module using a solar pond.

[0042] The compressed gas distillation seawater desalination module includes an absorber 101 , a generator 102 , a condenser 103 , a gas-liquid separator 104 , a fresh water storage tank 105 , a solution pump 108 and a solution throttle valve 109 .

[0043] The absorber 101 includes a cold source inlet, a cold source outlet, a water vapor inlet, a concentrated solution inlet, and a dilute solution outlet; the generator 102 includes a heat source inlet, a heat source outlet, a water vapor outlet, a dilute solution inlet, and a concentrated solution outlet. The solution pump 108 is connected between the dilute solution outlet of the absorber 101 and the dilute solution inlet of the generator 102; the condenser 103 is connected between the water vapor outlet of the generator 102 and the fresh water storage tank 105; the gas-liquid separator 104 is connected between the fresh water outlet of the condenser 103 and the water vapor inlet of the absorber 101; and the solution throttle valve 109 is connected between the concentrated solution outlet of the absorber 101 and the concentrated solution inlet of the generator 102.

[0044] The dilute solution outlet of the absorber 101, the solution pump 108, the concentrated solution outlet of the generator 102 and the solution throttle valve 109 are connected in sequence to form an absorbent lithium bromide solution circuit, wherein the solution pump 108 is used to boost and transport the dilute lithium bromide solution at the dilute solution outlet of the absorber 101, enter the generator 102 to exchange heat with the warm seawater at the bottom of the solar pond to form a gas-liquid two-phase mixture, water vapor flows out from the water vapor outlet of the generator 102, and the lithium bromide concentrated solution flows out from the concentrated solution outlet of the generator 102; the deep cold seawater 112 enters the absorber 101 as a cold source, and after being diverted by the diverter 106, it enters the condenser 103 to play the role of a cold source, and then is separated by the gas-liquid separator 104 to obtain water vapor. The water vapor outlet of the gas-liquid separator 104, the water vapor inlet of the absorber 101, the solution pump 108, the concentrated solution outlet of the generator 102, and the condenser 103 are connected in sequence to form a refrigerant water passage. The condenser condenses to obtain fresh water.

[0045] The solar thermal utilization module includes a solar pond 110 and a surface warm seawater pump 111. The solar pond 110 is connected between the surface warm seawater pump 111 and the heat source inlet of the generator 102.

[0046] Figure 2 It is demonstrated that the temperature difference assisted by low-pressure compression can drive the compressed gas distillation seawater desalination system. On the basis of the absorption compressed gas distillation desalination cycle, an additional low-pressure compressor 114 is added. The low-pressure compressor 114 is installed between the absorber 101 and the gas-liquid separator 104 to increase the pressure difference between the system flash pressure and the condensation pressure, thereby increasing the fresh water yield.

[0047] Figure 3 It is demonstrated that the temperature difference assisted by high-pressure compression can drive the compressed gas distillation seawater desalination system. On the basis of the absorption compressed gas distillation desalination cycle, an additional high-pressure compressor 115 is added and installed between the generator 102 and the condenser 103 to increase the heat of the cold seawater at the condenser outlet, thereby improving the fresh water yield.

[0048] Figure 4The process of lifting deep cold seawater by natural pressure difference is demonstrated, which is realized by a cold seawater transport module using natural vacuum technology. The cold seawater transport module includes a transport pipe 401 and a reservoir 402. The transport pipe 401 connects the deep cold seawater and the reservoir 402. The pressure difference caused by the height difference H1 between the sea level 403 and the liquid level of the reservoir causes the deep cold seawater to flow naturally along the deep cold seawater transport pipe 401 from about 1,000 meters below the sea level into the reservoir 402. The energy consumption required to lift seawater from the seabed is avoided.

[0049] Figure 5 The process of vacuum pressure difference lifting of deep cold seawater is shown. The cold seawater is naturally lifted to a height H2 through a pressure difference of about one atmosphere between the gas-liquid separator 104 and the water reservoir 402 at the generator outlet, and the cold seawater flows out at the outlet of the gas-liquid separator 104 under the action of gravity, completing the transportation of cold seawater. This process increases the resistance pump 501 to overcome the flow resistance in the pipe. The absorber 101, diverter 106 and condenser 103 between the water reservoir 402 and the gas-liquid separator 104 are omitted in the figure.

[0050] Figure 6 The PT diagram of the temperature difference-driven compressed gas distillation desalination system is shown: a schematic diagram of the temperature and pressure relationship at each main state point of the system. Assuming that the condenser 103 and the gas-liquid separator 104 are both placed at a height of 10.33m, the air pressure in the cycle is balanced, and the throttle valve 107 at the condenser inlet is normally open. The deep cold seawater 112 is heated to the second state S2 by the generator 101 at equal pressure in the first state S1, and then passes through the diverter 106 to the fourth state S4, and then passes through the condenser 103 to cool down and reduce the pressure to the sixth state S6. After entering the gas-liquid separator 104 and being separated to the seventh state S7, it is mixed with the solvent in the twelfth state S12 (the outlet of the solution throttle valve 109) to the eighth state S8. It is heated and pressurized to the ninth state S9 by the concentrated solution pump 108. The mixed solution in the 9th state S9 is heated by the absorber 101 to obtain the lithium bromide concentrated solution in the 11th state S11 and the water vapor in the 10th state S10; the lithium bromide concentrated solution is throttled to the 12th state S12 by the solution throttle valve. The water vapor in the 10th state S10 is condensed by the condenser to obtain fresh water in the 16th state S16. Specific embodiments

[0052] Taking the South China Sea as an example, for the case without compressor assistance, such as Figure 1As shown, the temperature difference can drive the compressed gas distillation desalination system. The given design parameters are as follows: the circulating working fluid uses lithium bromide-water binary working fluid (lithium bromide: water = 1:9). The generator pressure is 2kPa and the absorber pressure is 0.9kPa. The warm seawater pipeline inlet is located at 15m below sea level. The temperature of the warm seawater entering the solar pool is 29℃, and it is heated to 38℃ at the bottom of the solar pool. The warm seawater at the bottom of the solar pool releases heat in the generator and the temperature drops to 4℃. The deep cold seawater riser is located 800m below sea level, where the water temperature is stable at 4℃. The temperature of the cold seawater at the absorber inlet is 4℃, and the temperature is increased by 3℃. The deep cold seawater flow rate is 20tons / day. Through calculation, when 0.15538tons / day is left after passing through the diverter, the energy conservation condition is met. The remaining cold seawater can be used for comprehensive utilization of power generation and refrigeration.

[0053] Based on the above design parameters, the energy conservation principle is used to establish a process calculation model (as shown in Table 1), and the state point thermodynamic parameters are calculated (the main state point thermodynamic parameters are shown in Table 2);

[0054] Table 1 Energy balance equations for each module

[0055]

[0056] Note: The subscript HEX stands for heat exchanger, H and C stand for hot flow and cold flow, p stands for pump, and s stands for isentropic. Q, h, η represent energy (kJ), mass flow rate (kg / s), enthalpy (kJ / kg), and efficiency, respectively.

[0057] Table 2 Thermodynamic parameters of main state points of ocean temperature difference driven compression assisted absorption refrigeration cycle

[0058]

[0059]

[0060] Note: Tons here is a US unit of weight. Its definition is that 1 short ton is equal to 907.2 kilograms.

[0061] During the process, the low-pressure water vapor entering the absorber 101 is mixed with the lithium bromide concentrated solution during the absorption process, and heat is exchanged with the deep cold seawater to obtain a lithium bromide dilute solution. The flow rate of the lithium bromide dilute solution is the sum of the flow rates of the low-pressure water vapor 7 and the lithium bromide concentrated solution. After the deep cold seawater is diverted by the diverter, 0.15538 tons / day of seawater is left. It enters the condenser inlet throttle valve 107 to reduce the pressure to near vacuum (900Pa), and in the condenser, it is countercurrently heat-exchanged with the high-pressure water vapor flowing out of the generator outlet at a constant pressure to form a gas-liquid coexistence state, and then enters the gas-liquid separator 104. The separated low-pressure water vapor is mixed with the lithium bromide solution at the outlet of the solution throttle valve 109 to form a gas-liquid two-phase mixture. Then it enters the absorber 101 and exchanges heat with 4℃ cold seawater in countercurrent, so that the water vapor is completely absorbed to obtain a dilute lithium bromide solution; the dilute lithium bromide solution is pressurized to 2kPa and enters the generator 102, and the warm seawater at the bottom of the solar pool 110 releases heat in the generator 102 to obtain water vapor high pressure and lithium bromide concentrated solution. The lithium bromide concentrated solution coming out of the generator 102 is throttled to 900Pa by the solution throttle valve 109 and then enters the absorber 101 to absorb the low-pressure water vapor from the gas-liquid separator 104, completing the solution cycle. The high-pressure water vapor at the outlet of the generator 102 enters the condenser 103 for heat exchange and complete condensation to obtain fresh water.

[0062] In addition, the calculation formulas and results of the heat load of each major equipment are shown in Table 3.

[0063] Table 3 Heat load or power consumption of main equipment in ocean temperature difference driven compression assisted absorption refrigeration cycle

[0064]

[0065] The above specific implementation methods are only for illustrating the technical concept and structural features of the present invention, and the purpose is to enable relevant persons familiar with this technology to implement it. However, the above content does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A temperature difference driven compressed air distillation seawater desalination system, comprising a compressed air distillation seawater desalination module, characterized in that: The compressed gas distillation seawater desalination module comprises an absorber, a generator, a condenser, a gas-liquid separator, a fresh water storage tank, a solution pump and a solution throttle valve; the absorber comprises a cold source inlet, a cold source outlet, a water vapor inlet, a concentrated solution inlet and a dilute solution outlet; the generator comprises a heat source inlet, a heat source outlet, a water vapor outlet, a dilute solution inlet and a concentrated solution outlet; the solution pump is connected between the dilute solution outlet of the absorber and the dilute solution inlet of the generator; the condenser is connected between the water vapor outlet of the generator and the fresh water storage tank; the gas-liquid separator is connected between the fresh water outlet of the condenser and the water vapor inlet of the absorber; the solution throttle valve is connected between the concentrated solution outlet of the absorber and the concentrated solution inlet of the generator; deep cold seawater is introduced into the cold source inlet of the absorber; surface warm seawater is introduced into the heat source inlet of the generator; The low-pressure water vapor introduced from the water vapor inlet of the absorber is absorbed by the concentrated solution in the absorber to form a dilute solution. The heat released during the absorption process is taken away by the deep cold seawater. Subsequently, the dilute solution enters the generator under the action of the solution pump to exchange heat with the surface warm seawater to form a two-phase mixture consisting of a concentrated solution and high-pressure water vapor. The concentrated solution is reduced in pressure by a throttle valve and then enters the absorber to circulate and absorb the low-pressure water vapor. The high-pressure water vapor enters the condenser and is condensed into fresh water.

2. The temperature difference energy driven compressed gas distillation seawater desalination system according to claim 1, characterized in that: A low-pressure compressor for reducing the flash pressure is arranged between the gas-liquid separator and the water vapor inlet of the absorber.

3. The temperature difference energy driven compressed gas distillation seawater desalination system according to claim 1, characterized in that: A high-pressure compressor is arranged between the generator and the condenser for increasing the heat load of the condenser.

4. The temperature difference energy driven compressed gas distillation seawater desalination system according to claim 1, characterized in that: The temperature difference energy driven compressed gas distillation seawater desalination system also includes a cold seawater delivery module for delivering cold seawater.

5. The temperature difference energy driven compressed gas distillation seawater desalination system according to claim 4, characterized in that: The cold seawater transport module includes a transport pipe and a water reservoir, wherein the transport pipe connects the deep cold seawater and the water reservoir; the deep cold seawater naturally flows into the water reservoir from below the sea level along the deep cold seawater transport pipe due to the pressure difference H1 between the sea level and the liquid level of the water reservoir.

6. The temperature difference energy driven compressed gas distillation seawater desalination system according to claim 1, characterized in that: The temperature difference energy driven compressed gas distillation seawater desalination system also includes a solar thermal utilization module for providing warm seawater.

7. The temperature difference energy driven compressed gas distillation seawater desalination system according to claim 6, characterized in that: The solar thermal utilization module comprises a solar pool and a surface warm seawater pump; the solar pool is connected between the surface warm seawater pump and the heat source inlet of the generator.

8. The temperature difference energy driven compressed gas distillation seawater desalination system according to claim 7, characterized in that: By introducing surface warm seawater into the solar pool for heat storage, a salt solution concentration gradient is formed in the solar pool. As the density of the salt water increases with the salt content, the concentrated brine at the bottom absorbs solar energy and its temperature rises, achieving the effect of storing solar energy.

9. The temperature difference energy driven compressed gas distillation seawater desalination system according to claim 1, characterized in that: The solution circulating between the absorber and the generator is a concentrated lithium bromide solution.

10. A seawater desalination method based on the temperature difference energy driven compressed gas distillation seawater desalination device according to any one of claims 1 to 9, characterized in that: include: The deep cold seawater enters the generator from the first state S1 and is heated isobarically to the second state S2; The seawater in the second state S2 passes through the diverter to the fourth state S4; The seawater in the fourth state S4 is cooled and decompressed by the condenser 1 to the sixth state S6; The seawater in the sixth state S6 enters the gas-liquid separator and is separated into low-pressure water vapor in the seventh state S7; The low-pressure water vapor in the seventh state S7 is mixed with the lithium bromide concentrated solution in the twelfth state S12 to form a lithium bromide dilute solution in the eighth state S8; The dilute lithium bromide solution in the eighth state S8 is heated and pressurized by a solution pump to become a dilute lithium bromide solution in the ninth state S9; The dilute lithium bromide solution in the ninth state S9 is heated in the absorber to obtain a concentrated lithium bromide solution in the eleventh state S11 and high-pressure water vapor in the tenth state S10; The lithium bromide concentrated solution in the 11th state is throttled to the lithium bromide concentrated solution in the 12th state S12 through the solution throttle valve; The high-pressure steam in the 10th state S10 is condensed by the condenser to obtain fresh water in the 16th state.

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