1. A solar energy and waste heat flat-plate type membrane distillation and heat recovery system thereof is characterized by comprising a membrane distillation device, a heating module and a heat recovery module, wherein a hot seawater flow channel (3) of the membrane distillation device is connected with a third heat exchanger (133); the heating module is connected with the third heat exchanger (133) for heat exchange; the heat recovery module comprises a heat regenerator (132), a second three-way control valve (122) and a third three-way control valve (123), and a third branch S is connected and branched with a cold seawater flow passage (5) and the second three-way control valve (122) of the membrane distillation device₃Said third substream S₃Is connected with a regenerator (132), the regenerator (132) is connected with a sixth branch S₆Is connected with the third heat exchanger (133) through a third three-way control valve (123), and the third heat exchanger (133) is connected with a hot seawater flow channel (3) of the membrane distillation device; the outlet of the hot seawater flow channel (3) is connected with the heat regenerator (132), and the heat regenerator (132) passes through a fifth branch S₅And a sixth branch S passing through the third three-way control valve (123)₆After being merged, the third heat exchanger (133) is connected.

2. Solar energy and waste heat flat-plate membrane distillation and heat recovery system according to claim 1, characterized in that the cold seawater reservoir (9) is connected to a first three-way control valve (121) via a first pump 111, said first three-way control valve (121) being branched into a first branch S and a first branch S₁And a second substream S₂Said first substream S₁The second branch stream S2 is connected with an inlet of a cold seawater flow channel (5) of the membrane distillation device; the fresh water reservoir (10) is connected with the first heat exchanger (131) after being powered by a third pump (113), and the first heat exchanger (131) is connected with a gap layer (4) of the membrane distillation device; the fresh water reservoir (10) is provided with an eighth branch S₈Is connected with the gap layer (4) of the membrane distillation device; the filmThe lower drainage hole of the clearance layer (4) of the distillation device is connected with the fresh water reservoir (10).

3. The solar energy and waste heat flat plate membrane distillation and heat recovery system thereof as claimed in claim 2, wherein the heating module comprises a solar heating device, a heat source and a heat storage tank (143); the solar heating module and the heat source are respectively connected with the heat storage tank (143) through a circulating heat exchange pipeline, and the heat storage tank (143) is connected with the third heat exchanger (133) through a circulating pipeline.

4. The flat-plate membrane distillation and heat recovery system using solar energy and waste heat as claimed in claim 3, wherein the solar heating device comprises a solar heat collecting tube (141) and a second heat exchanger (142), the solar heat collecting tube (141) and the first circulating medium pipeline S₁₀Connected, the first circulating medium pipeline S₁₀Is connected with a second heat exchanger (142), and a second circulating working medium pipeline S is arranged between the second heat exchanger (142) and the heat storage pool (143)₉The connection forms a circulating heat exchange pipeline.

5. The flat-plate membrane distillation and heat recovery system using solar energy and waste heat according to claim 1, wherein the membrane distillation device comprises a hydrophobic microporous membrane (1), a condensation plate (2), a hot seawater flow channel (3), an interstitial layer (4), a cold seawater flow channel (5) and a fresh water diversion pipeline (8), the interstitial layer (4) is arranged between the hydrophobic microporous membrane (1) and the condensation plate (2), the hot seawater flow channel (3) is arranged at the other side of the hydrophobic microporous membrane (1) opposite to the condensation plate (2), and the cold seawater flow channel (5) is arranged at the other side of the condensation plate (2) opposite to the hydrophobic microporous membrane (1); the condensing plate (2) is provided with a shunting hole (6), and the shunting hole (6) is connected with the fresh water shunting pipeline (8).

6. The solar energy and waste heat flat plate type membrane distillation and heat recovery system thereof as claimed in claim 1, wherein the membrane distillation device is a combined membrane distillation device; the combined membrane distillation device comprises a top membrane distillation unit, an intermediate membrane distillation unit and a bottom membrane distillation unit, wherein the top membrane distillation unit comprises a hydrophobic microporous membrane, a condensing plate, a hot seawater flow channel, a top gap layer, a cold seawater flow channel and a fresh water diversion pipeline, the top gap layer is arranged between the hydrophobic microporous membrane and the condensing plate, the hot seawater flow channel is arranged at the other side of the hydrophobic microporous membrane relative to the condensing plate, the cold seawater flow channel is arranged at the other side of the condensing plate relative to the hydrophobic microporous membrane, and the top gap layer is in contact with the condensing plate. The condensing plate is provided with shunting holes, the shunting holes are connected with the fresh water shunting pipelines, and the fresh water shunting pipelines are connected with the fresh water reservoir; and the lower drainage hole of the top gap layer is communicated with the middle gap layer. The middle-layer membrane distillation unit comprises a hydrophobic microporous membrane, a condensing plate, a hot seawater flow channel, a middle-layer gap layer and a cold seawater flow channel, wherein the middle-layer gap layer is arranged between the hydrophobic microporous membrane and the condensing plate, the hot seawater flow channel is positioned at the other side of the hydrophobic microporous membrane relative to the condensing plate, and the cold seawater flow channel is positioned at the other side of the condensing plate relative to the hydrophobic microporous membrane; the bottom layer membrane distillation unit comprises a hydrophobic microporous membrane, a condensing plate, a hot seawater flow channel, a bottom layer gap layer and a cold seawater flow channel, wherein the bottom layer gap layer is arranged between the hydrophobic microporous membrane and the condensing plate, the hot seawater flow channel is positioned at the other side of the hydrophobic microporous membrane relative to the condensing plate, and the cold seawater flow channel is positioned at the other side of the condensing plate relative to the hydrophobic microporous membrane; the fresh water reservoir is connected with the first heat exchanger, and the first heat exchanger is connected with the bottom clearance layer through a third pump and a sixth control valve; the bottom gap layer is connected with the inlet of the fresh water reservoir through a seventh control valve; and a bottom clearance layer lower drainage hole is arranged below the bottom clearance layer and is connected with the fresh water reservoir through an eighth control valve.

7. The solar energy and waste heat flat plate type membrane distillation and heat recovery system thereof as claimed in claim 1, wherein the membrane distillation device is a combined membrane distillation device; the combined membrane distillation device comprises a hydrophobic microporous membrane (1) and a condensation plate (2), wherein one side of the hydrophobic microporous membrane (1) forms a hot seawater flow channel (3), a gap layer (4) is arranged between the hydrophobic microporous membrane (1) and the condensation plate (2), and the other side of the condensation plate (2) opposite to the gap layer (4) forms a cold seawater flow channel (5); two partition plates are arranged in the gap layer (4) and are divided into a top gap layer (14), a middle gap layer (15) and a bottom gap layer (16) from top to bottom, a top gap layer lower drainage hole (26) is arranged on the partition plate between the top gap layer (14) and the middle gap layer (15) and communicated with each other, and a top gap layer upper drainage hole (28) is arranged on the top gap layer (14); the middle gap layer (15) is provided with a middle gap layer liquid discharging hole (29), and the bottom gap layer (16) is provided with a bottom gap layer liquid discharging hole (30).

8. The flat-plate membrane distillation and heat recovery system using solar energy and residual heat as claimed in claim 7, wherein the upper end of the hot seawater channel (3) is provided with a hot seawater channel inlet (21); a hot seawater runner outlet (22) is arranged at the lower end of the hot seawater runner (3); cold sea water runner (5) from top to bottom has set gradually cold sea water runner export (24), fresh water shunt canals export (25) and cold sea water runner import (23), condensation plate piece (2) set up two diffluence orifices (6) on top interstitial layer (14), diffluence orifice (6) are connected with fresh water shunt canals (8), fresh water shunt canals (8) are connected with fresh water shunt canals export (25).

9. An operation mode of a solar energy and waste heat flat plate type membrane distillation and a heat recovery system thereof is characterized in that based on the structure of the solar energy and waste heat flat plate type membrane distillation and the heat recovery system thereof as claimed in any one of claims 1 to 8, the operation mode comprises three different operation modes: the operation under the working conditions of sufficient sunlight and high-temperature waste heat is coped with; the system can be used for the operation under the working conditions of less sunlight and medium-temperature waste heat and the operation under the working conditions of cloudy days or nights and low-temperature waste heat.

10. The operation mode of a solar energy and residual heat flat plate type membrane distillation and its heat recovery system according to claim 9, wherein when the heat source temperature is higher than 70 ℃, the lower outlet flow ratio of the third three-way control valve (123) is 0.6-0.9, the right outlet flow ratio of the first three-way control valve (121) is 1, and the left outlet flow ratio of the second three-way control valve (122) is 0.1-0.4; when the ambient temperature is lower than 70 ℃ but higher than 50 ℃, the lower outlet flow ratio of the third three-way control valve (123) is 0.3 to 0.6, the right outlet flow ratio of the first three-way control valve (121) is 1, and the left outlet flow ratio of the second three-way control valve (122) is 0.4 to 0.7; when the ambient temperature is lower than 50 ℃, the lower outlet flow ratio of the third three-way control valve (123) is 0.1-0.3, the right outlet flow ratio of the first three-way control valve (121) is 0.7-0.9, and the left outlet flow ratio of the second three-way control valve (122) is 1;

when the temperature of the heat source is higher than 70 ℃ based on the structure of the combined membrane distillation apparatus, the right outlet flow ratio of the third three-way control valve (123) is 0.6 to 0.9, the upper outlet flow ratio of the first three-way control valve (121) is 0.6 to 0.8, and the lower outlet flow ratio of the second three-way control valve (122) is 0.2 to 0.5; when the ambient temperature is lower than 70 ℃ but higher than 50 ℃, the right outlet flow ratio of the third three-way control valve (123) is 0.3-0.6, the upper outlet flow ratio of the first three-way control valve (121) is 0.8-1, and the lower outlet flow ratio of the second three-way control valve (122) is 0.5-0.7; when the ambient temperature is lower than 50 ℃, the right outlet flow ratio of the third three-way control valve (123) is 0.1 to 0.3, the right outlet flow ratio of the first three-way control valve (121) is 0.7 to 0.9, and the lower outlet flow ratio of the second three-way control valve (122) is 1.

Background

Membrane distillation is a seawater desalination technology driven by low-grade heat energy. The working principle is as follows: the vapor generated by the evaporation of the hot seawater at the side with higher temperature of the hydrophobic membrane permeates the micropores of the membrane to be diffused to the other side with lower temperature under the driving of the steam pressure difference, and other liquid can not enter the micropores due to the hydrophobicity of the membrane so as to realize the separation. The membrane distillation requires low grade heat energy and high rejection rate of the hydrophobic membrane, so that the membrane distillation has great development potential in the field of seawater desalination treatment.

At present, common membrane distillation types mainly include air gap type membrane distillation, direct contact type membrane distillation, penetrating fluid gap type membrane distillation and the like. An air layer (namely an air gap) exists between the cold-side membrane surface of the air-gap type flat membrane distillation and the condensate, and steam passes through the membrane holes and then reaches the cooling wall surface through the air gap to exchange heat with cooling water so as to be condensed. Because the thermal resistance of the air gap is larger, the heat conducted from the hot side to the cold side through the membrane is reduced, and the energy utilization efficiency is improved. But due to the presence of air gaps, the resistance to vapor diffusion increases, resulting in a decrease in the rate of water production. In addition, a liquid film (or liquid drops) formed by the steam condensed on the cooling wall surface increases the thermal resistance between the steam and the cooling wall surface and reduces the condensation area of the steam, so that the steam condensation rate is reduced, and the water production efficiency is influenced. Meanwhile, when the thickness of the liquid film reaches a certain degree, the liquid film can contact with the hydrophobic film to form a heat bridge, so that the heat leakage quantity is increased.

The steam of the direct contact type membrane distillation is directly mixed with cooling water for condensation after passing through the membrane, and the condensation efficiency is higher than that of the air gap type membrane distillation, so that the water production rate is higher. But because the cooling water is in direct contact with the film, the heat leakage is more obvious, the heat loss is larger, and the energy utilization efficiency is low.

Permeate gap membrane distillation can be considered as a compromise between direct contact membrane distillation and air gap membrane distillation. The structure of the membrane distillation device is similar to that of air gap type membrane distillation, but the gap layer is filled with penetrating fluid (water vapor condensate), and because the steam passes through the membrane and is directly mixed with the penetrating fluid for condensation, the steam does not need to further penetrate through the air gap to be condensed on a cooling wall surface, the mass transfer resistance of the process is reduced, the condensation area of the water vapor is increased, and the water production rate is higher than that of the air gap type membrane distillation device but lower than that of a direct contact type membrane distillation device. In addition, since the cooling water is not in direct contact with the membrane, the heat leakage defect is improved, and the thermal efficiency is higher than that of direct contact membrane distillation but lower than that of air gap membrane distillation.

The three membrane distillation types are different in application range, for example, direct contact membrane distillation is suitable for the working condition with lower heat source temperature to improve the water production rate, and air gap membrane distillation is suitable for the working condition with higher heat source temperature to reduce heat leakage. Because the membrane distillation adopts low-grade heat energy with unstable temperature and load, such as solar energy, waste heat and the like, the existing single membrane distillation mode is difficult to adapt to different working conditions.

Disclosure of Invention

Aiming at the defects of liquid film accumulation, heat leakage of a heat bridge and the like in the prior art, the invention aims to provide a solar energy and waste heat flat-plate type membrane distillation and heat recovery system.

The invention also aims to provide an operation mode of the solar energy and waste heat flat-plate type membrane distillation and heat recovery system.

In order to achieve the purpose of the invention, the invention adopts the technical scheme that: a solar energy and waste heat flat-plate membrane distillation and heat recovery system thereof comprises a membrane distillation device, a heating module and a heat recovery module, wherein a hot seawater flow channel 3 of the membrane distillation device is connected with a third heat exchanger 133; the heating module is connected with the third heat exchanger 133 for heat exchange; the heat recovery module comprises a heat regenerator 132, a second three-way control valve 122 and a third three-way control valve 123, and a third branch S is branched from the cold seawater flow passage 5 of the membrane distillation device connected with the second three-way control valve 122₃Said third substream S₃Connected to the regenerator 132, said regenerator 132 being fed by a sixth substream S₆Is connected with the third heat exchanger 133 through a third three-way control valve 123, and the third heat exchanger 133 is connected with a hot seawater flow channel 3 of the membrane distillation device; the outlet of the hot seawater flow passage 3 is connected with the heat regenerator 132, and the heat regenerator 132 passes through a fifth branch S₅And the sixth branch S passing through the third three-way control valve 123₆And then, the combined gas is connected to the third heat exchanger 133. The heat recovery module takes a heat regenerator 132 as a medium, and controls the flow rate of material flow through a second three-way control valve 122 and a third three-way control valve 123, so as to adjust the system waste heat (heat) under different heat source conditionsWaste heat of the outlet stream of the seawater runner).

The cold seawater reservoir 9 is connected via a first pump 111 to a first three-way control valve 121, said first three-way control valve 121 branching off into a first branch S₁And a second substream S₂Said first substream S₁Is connected with the first heat exchanger 131, and the second branch S₂Connected with the inlet of the cold seawater flow passage 5 of the membrane distillation device, and the third three-way control valve 123 divides the seventh branch S₇A direct exhaust system; the fresh water reservoir 10 is powered by a third pump 113 and then is connected with the first heat exchanger 131, and the first heat exchanger 131 is connected with the gap layer 4 of the membrane distillation device through a fourth control valve 104; the fresh water reservoir 10 is provided with an eighth branch S₈Is connected with the gap layer 4 of the membrane distillation device through a third control valve 103; the gap layer 4 of the membrane distillation apparatus is connected to the fresh water reservoir 10 through a first control valve 101 and a second pump 112 for collecting fresh water.

The heating module comprises a solar heating device, a heat source and a heat storage pool 143; the solar heating module and the heat source are respectively connected with the heat storage tank 143 through a circulating heat exchange pipeline, and the heat storage tank 143 is connected with the third heat exchanger 133 through a circulating pipeline.

The solar heating device comprises a solar heat collecting pipe 141 and a second heat exchanger 142, wherein the solar heat collecting pipe 141 and a first circulating working medium pipeline S₁₀Connected, the first circulating medium pipeline S₁₀Is connected with a second heat exchanger 142, and a second circulating working medium pipeline S is arranged between the second heat exchanger 142 and the heat storage tank 143₉The connection forms a circulating heat exchange pipeline.

The heat source 144 is connected with the heat storage tank 143 through a circulating heat exchange pipeline for heat exchange.

The membrane distillation device comprises a hydrophobic microporous membrane 1, a condensation plate 2, a hot seawater flow channel 3, an interval layer 4, a cold seawater flow channel 5 and a fresh water diversion channel 8, wherein the interval layer 4 is arranged between the hydrophobic microporous membrane 1 and the condensation plate 2, the hot seawater flow channel 3 is positioned at the other side of the hydrophobic microporous membrane 1 opposite to the condensation plate 2, the cold seawater flow channel 5 is positioned at the other side of the condensation plate 2 opposite to the hydrophobic microporous membrane 1, and the interval layer 4 is in contact with the condensation plate 2.

The condensing plate 2 is provided with a diversion hole 6, the diversion hole 6 is connected with the fresh water diversion pipeline 8, and the lower liquid discharge hole of the gap layer 4 is connected with a fresh water reservoir 10 through a first control valve 101; the outlet of the fresh water diversion pipeline 8 is connected with the outlet of the first control valve 101 through the second control valve 102 and is converged and connected with the fresh water reservoir 10 through the second pump 112.

The condensation plate 2 is provided with corrugations 7 on its outer surface.

The membrane distillation device is a combined membrane distillation device.

The combined membrane distillation device comprises a top membrane distillation unit, an intermediate membrane distillation unit and a bottom membrane distillation unit, wherein the top membrane distillation unit comprises a hydrophobic microporous membrane, a condensing plate piece, a hot seawater flow channel, a top gap layer 14, a cold seawater flow channel and a fresh water diversion pipeline, the top gap layer 14 is arranged between the hydrophobic microporous membrane and the condensing plate piece, the hot seawater flow channel is arranged at the other side of the hydrophobic microporous membrane relative to the condensing plate piece, the cold seawater flow channel is arranged at the other side of the condensing plate piece relative to the hydrophobic microporous membrane, and the top gap layer is in contact with the condensing plate piece. The condensing plate is provided with a diversion hole 6, the diversion hole 6 is connected with the fresh water diversion pipeline 8, and the fresh water diversion pipeline 8 is connected with the fresh water reservoir 10 through a fifth control valve 105 and a second pump 112. And the lower drainage hole of the top gap layer is communicated with the middle gap layer. The middle-layer membrane distillation unit comprises a hydrophobic microporous membrane, a condensing plate, a hot seawater flow channel, a middle-layer gap layer and a cold seawater flow channel, wherein the middle-layer gap layer is arranged between the hydrophobic microporous membrane and the condensing plate, the hot seawater flow channel is positioned at the other side, opposite to the condensing plate, of the hydrophobic microporous membrane, and the cold seawater flow channel is positioned at the other side, opposite to the hydrophobic microporous membrane, of the condensing plate. The middle gap layer is provided with a middle gap layer liquid drainage hole, and the middle gap layer liquid drainage hole is connected with the water storage tank 10; the bottom layer membrane distillation unit comprises a hydrophobic microporous membrane, a condensing plate, a hot seawater flow channel, a bottom layer gap layer and a cold seawater flow channel, wherein the bottom layer gap layer is arranged between the hydrophobic microporous membrane and the condensing plate, the hot seawater flow channel is arranged at the other side of the hydrophobic microporous membrane relative to the condensing plate, and the cold seawater flow channel is arranged at the other side of the condensing plate relative to the hydrophobic microporous membrane. The fresh water reservoir 10 is connected with a first heat exchanger 131, and the first heat exchanger 131 is connected with the bottom clearance layer through a third pump 113 and a sixth control valve 106; the bottom gap layer is connected to the fresh water reservoir 10 inlet via a seventh control valve 107. And a bottom clearance layer lower drainage hole is arranged below the bottom clearance layer and is connected with the fresh water reservoir 10 through an eighth control valve 108.

The combined membrane distillation device comprises a hydrophobic microporous membrane 1 and a condensing sheet 2, wherein one side of the hydrophobic microporous membrane 1 forms a hot seawater flow channel 3, a gap layer 4 is arranged between the hydrophobic microporous membrane 1 and the condensing sheet 2, and the other side of the condensing sheet 2 opposite to the gap layer 4 forms a cold seawater flow channel 5; two partition boards are arranged in the gap layer 4 and are separated from top to bottom into a top gap layer 14, a middle gap layer 15 and a bottom gap layer 16, the partition boards between the top gap layer 14 and the middle gap layer 15 are provided with top gap layer lower drainage holes 26 which are communicated, the top gap layer 14 is provided with top gap layer upper drainage holes 28, the middle gap layer 15 is provided with middle gap layer drainage holes 29, and the bottom gap layer 16 is provided with bottom gap layer upper drainage holes 30.

The upper end of the hot seawater runner 3 is provided with a hot seawater runner inlet 21; a hot seawater channel outlet 22 is arranged at the lower end of the hot seawater channel 3; cold sea water runner 5 has set gradually cold sea water runner export 24, fresh water shunt tubes say export 25 and cold sea water runner import 23 from top to bottom and fresh water shunt tubes say export 25, condensation plate piece 2 sets up two diffluence orifices 6 on top clearance layer 14, diffluence orifices 6 is connected with fresh water shunt tubes way 8, fresh water shunt tubes way 8 is connected with fresh water shunt tubes say export 25.

The utility model provides a solar energy adds flat membrane distillation of waste heat and heat recovery system's operational mode, is based on solar energy adds flat membrane distillation of waste heat and heat recovery system structure thereof, and it includes that three kinds of different operational modes are respectively: the operation under the working conditions of sufficient sunlight and high-temperature waste heat is coped with; the system can be used for the operation under the working conditions of less sunlight and medium-temperature waste heat and the operation under the working conditions of cloudy days or nights and low-temperature waste heat.

In the operation mode of the solar energy and waste heat flat-plate type membrane distillation and heat recovery system thereof, when the temperature of a heat source is higher than 70 ℃, the lower outlet flow ratio of the third three-way control valve 123 is 0.6-0.9, the right outlet flow ratio of the first three-way control valve 121 is 1, and the left outlet flow ratio of the second three-way control valve 122 is 0.1-0.4; when the ambient temperature is lower than 70 ℃ but higher than 50 ℃, the lower outlet flow ratio of the third three-way control valve 123 is 0.3 to 0.6, the right outlet flow ratio of the first three-way control valve 121 is 1, and the left outlet flow ratio of the second three-way control valve 122 is 0.4 to 0.7; when the ambient temperature is lower than 50 c, the lower outlet flow ratio of the third three-way control valve 123 is 0.1 to 0.3, the right outlet flow ratio of the first three-way control valve 121 is 0.7 to 0.9, and the left outlet flow ratio of the second three-way control valve 122 is 1.

The operation mode of the solar energy and waste heat flat-plate type membrane distillation and heat recovery system thereof is based on the structure of the combined type membrane distillation device, when the temperature of a heat source is higher than 70 ℃, the flow ratio of a right outlet of the third three-way control valve 123 is 0.6-0.9, the flow ratio of an upper outlet of the first three-way control valve 121 is 0.6-0.8, and the flow ratio of a lower outlet of the second three-way control valve 122 is 0.2-0.5; when the ambient temperature is lower than 70 ℃ but higher than 50 ℃, the right outlet flow ratio of the third three-way control valve 123 is 0.3 to 0.6, the upper outlet flow ratio of the first three-way control valve 121 is 0.8 to 1, and the lower outlet flow ratio of the second three-way control valve 122 is 0.5 to 0.7; when the ambient temperature is lower than 50 c, the right outlet flow ratio of the third three-way control valve 123 is 0.1 to 0.3, the right outlet flow ratio of the first three-way control valve 121 is 0.7 to 0.9, and the lower outlet flow ratio of the second three-way control valve 122 is 1.

The invention adopts a multi-stage flow-dividing cooling plate structure to reduce the accumulation of liquid films and the formation of a heat bridge; aiming at the problem that a single membrane distillation mode is difficult to adapt to variable working conditions taking solar energy and waste heat as heat sources, a technical scheme of a multi-working mode membrane distillation module is adopted to ensure that the membrane distillation module can be mutually converted from an air gap type, a direct contact type and a penetrating fluid gap type; combining the structure of the air gap type membrane distillation multistage split flow cooling plate and strengthening the requirement of steam condensation in the direct contact type membrane distillation process; based on the integrated membrane distillation module, the flow suitable for multi-working-condition multi-mode membrane distillation is adopted, and the flow can be adjusted to adapt to the required working condition through a simple control valve; the combined membrane distillation module is adopted, and membrane distillation combination can be optimized according to the actual situation of a heat source; the multi-working mode membrane distillation and combined membrane distillation heat recovery structure is adopted, so that the aims of reducing the fire consumption of the system and improving the economy of the device can be achieved.

Compared with the prior art, the invention has the beneficial effects that:

(1) the traditional air gap type membrane distillation device is improved, the shunting holes are added on the condensing plate and connected with a product water outlet pipeline, and the condensed liquid is discharged midway, so that the effects of reducing the thickness of a liquid film, improving the condensing efficiency and preventing the heat bridge effect are realized;

(2) the single air gap type membrane distillation, the direct contact type membrane distillation or the penetrating fluid gap type membrane distillation all have the limitations, and the advantages of various membrane distillation are fully utilized through integrating the air gap type membrane distillation, the direct contact type membrane distillation and the penetrating fluid gap type membrane distillation, so that a multi-mode membrane distillation module is provided;

(3) the corrugated structure is adopted to replace a flat plate structure, on one hand, the corrugated structure can play a role in drainage and strengthen the drainage effect in the shunting process in the air gap type working mode, and on the other hand, the corrugated structure can increase the disturbance of cooling water in the direct contact type and penetrating fluid gap type working modes, so that the steam condensation effect and the water production rate are improved;

(4) the system can be adjusted according to different heat source temperatures in different time periods due to the characteristic that the temperatures of the solar energy and the waste heat source change along with time, when the temperature of the heat source is higher, air gap type membrane distillation or penetrating fluid gap type membrane distillation can be adopted to carry out a seawater desalination process through an adjusting control valve, when the temperature of the heat source is lower, direct contact type membrane distillation can be adopted to carry out the seawater desalination process, and when the temperature of the heat source is lower, a standby heat source is adopted to heat seawater;

(5) according to the characteristic that the three types of membrane distillation are respectively suitable for different heat source temperature conditions, a combined membrane distillation module is designed, and the structures of the combined membrane distillation module can be arranged and combined by adjusting a control valve, so that the combined membrane distillation module can be optimally combined according to the actual conditions of heat sources;

(6) by integrating the multi-mode membrane distillation and heat recovery method and designing an integrated multi-mode membrane distillation heat recovery system, the heat of phase change vaporization latent heat and solid heat conduction in the membrane distillation process can be effectively utilized, and the energy utilization efficiency is improved.

Drawings

FIG. 1 is a schematic system diagram of embodiment 1 of the present invention;

FIG. 2 is a schematic system diagram according to embodiment 2 of the present invention;

FIG. 3 is a perspective view of the combined membrane distillation apparatus;

fig. 4 is a schematic view of the structure of a condensation sheet in embodiment 2;

fig. 5 is a schematic view of the structure of a condensation sheet in embodiment 1;

FIG. 6 is a graph comparing the water production rate of a splitter plate air gap membrane distillation with a conventional air gap membrane distillation at different feed temperatures.

FIG. 7 is a control flow chart of example 1 of the present invention;

FIG. 8 is a control flow chart of example 2 of the present invention;

wherein, 1 is a hydrophobic microporous membrane, 2 is a condensing plate, 3 is a hot seawater flow channel, 4 is an interstitial layer, 5 is a cold seawater flow channel, 8 is a fresh water diversion pipeline, 9 is a cold seawater reservoir, 10 is a fresh water reservoir, 101 is a first control valve, 102 is a second control valve, 103 is a third control valve, 104 is a fourth control valve, 111 is a first pump, 112 is a second pump, 113 is a third pump, 121 is a first three-way control valve, 122 is a second three-way control valve, 123 is a third three-way control valve, 131 is a first heat exchanger, 133 is a third heat exchanger, 142 is a fourth heat exchanger, 132 is a heat regenerator, 141 is a solar heat collecting pipe, 143 is a heat storage tank, 144 is a heat source (a standby heat source or a waste heat source), m1 is a combined membrane distillation device, 14 is a top interstitial layer, 15 is a middle interstitial layer, 16 is a bottom interstitial layer, 105 is a fifth control valve, 106 is a sixth control valve, 107 is a seventh control valve, 108 is an eighth control valve, 109 is a ninth control valve, 21 is a hot seawater flow channel inlet, 22 is a hot seawater flow channel outlet, 23 is a cold seawater flow channel inlet, 24 is a cold seawater flow channel outlet, 25 is a fresh water diversion pipeline outlet, 26 is a top gap layer lower drainage hole, 27 is a bottom gap layer lower drainage hole, 28 is a top gap layer upper drainage hole, 29 is a middle gap layer drainage hole, 30 is a bottom gap layer upper drainage hole, 6 is a diversion hole, and 7 is a ripple.

Detailed Description

The drawings are for illustration purposes only and are not to be construed as limiting the invention; for a better understanding of the present embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The same or similar reference numbers in the drawings indicate the same or similar parts throughout the several views of the invention; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the devices of the accompanying drawings, the description is merely for convenience of description and simplicity of description, and it is not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore the positional relationships described in the drawings are for illustrative purposes only and are not to be construed as limitations of the present patent, and specific meanings of the terms described above will be understood by those of ordinary skill in the art according to specific circumstances.

Example 1

A solar energy and waste heat flat-plate membrane distillation and heat recovery system thereof is shown in figure 1 and comprises a membrane distillation device, a heating module and a heat recovery mechanism, wherein a hot seawater flow channel 3 of the membrane distillation device is connected with a third heat exchanger 133; the heating module is connected with the third heat exchanger 133 for heat exchange; the heat recovery module comprises a regenerator 132, a second regeneratorA three-way control valve 122 and a third three-way control valve 123, the outlet of the cold seawater channel 5 of the membrane distillation device is connected with the second three-way control valve 122 and is divided into a third branch S₃And a fourth substream S₄The fourth substream S₄Direct discharge system, the third substream S₃Connected to the regenerator 132, said regenerator 132 being fed by a sixth substream S₆Is connected with the third heat exchanger 133 through a third three-way control valve 123, and the third heat exchanger 133 is connected with the hot seawater flow passage 3 of the membrane distillation apparatus. The third three-way control valve 123 branches off the seventh branch S7 to directly exit the system. The outlet of the hot seawater flow passage 3 is connected with the heat regenerator 132, and the heat regenerator 132 passes through a fifth branch S₅And the sixth branch S passing through the third three-way control valve 123₆And then, the combined gas is connected to the third heat exchanger 133. The heat recovery module uses a heat regenerator 132 as a medium to control the flow rate of the material flow through a second three-way control valve 122 and a third three-way control valve 123, so as to achieve the effect of adjusting the recovery and utilization of the system waste heat (the waste heat of the material flow at the outlet of the hot seawater flow channel) under different heat source conditions. The cold seawater reservoir 9 is connected via a first pump 111 to a first three-way control valve 121, said first three-way control valve 121 branching off into a first branch S₁And a second substream S₂Said first substream S₁Is connected with the first heat exchanger 131, and the second branch S₂Connected with the inlet of the cold seawater flow passage 5 of the membrane distillation device, and the third three-way control valve 123 divides the seventh branch S₇A direct exhaust system; the fresh water reservoir 10 is powered by a third pump 113 and then is connected with the first heat exchanger 131, and the first heat exchanger 131 is connected with the gap layer 4 of the membrane distillation device through a fourth control valve 104; the fresh water reservoir 10 is provided with an eighth branch S₈Is connected with the gap layer 4 of the membrane distillation device through a third control valve 103; the gap layer 4 of the membrane distillation apparatus is connected to the fresh water reservoir 10 through a first control valve 101 and a second pump 112 for collecting fresh water.

The heating module comprises a solar heating device, a heat source and a heat storage pool 143; the solar heating module and the heat source are respectively connected with the heat storage tank 143 through a circulating heat exchange pipeline,the heat storage tank 143 is connected with the third heat exchanger 133 through a circulation pipeline. The solar heating device comprises a solar heat collecting pipe 141 and a second heat exchanger 142, wherein the solar heat collecting pipe 141 and a first circulating working medium pipeline S₁₀Connected, the first circulating medium pipeline S₁₀Is connected with a second heat exchanger 142, and a second circulating working medium pipeline S is arranged between the second heat exchanger 142 and the heat storage tank 143₉The connection forms a circulating heat exchange pipeline. First cycle working medium pipeline S₁₀The first circulating working medium in the solar heat collecting pipe 141 absorbs direct solar heat and then enters the second heat exchanger 142 for heat exchange, and the second circulating working medium pipeline S₉The second circulating working medium in the second heat exchanger 142 absorbs the heat released by the first circulating working medium, enters the heat storage tank 143, and then is in direct contact with the fifth branch S in the third heat exchanger 133₅Heat is released, seawater is preheated, and then the seawater sequentially passes through the heat storage tank 143 and the second heat exchanger 142 to form a circulating heat exchange process. The heat source 144 is connected with the heat storage tank 143 through a circulating heat exchange pipeline for heat exchange.

The membrane distillation device comprises a hydrophobic microporous membrane 1, a condensation plate 2, a hot seawater flow channel 3, an interval layer 4, a cold seawater flow channel 5 and a fresh water diversion channel 8, wherein the interval layer 4 is arranged between the hydrophobic microporous membrane 1 and the condensation plate 2, the hot seawater flow channel 3 is positioned at the other side of the hydrophobic microporous membrane 1 opposite to the condensation plate 2, the cold seawater flow channel 5 is positioned at the other side of the condensation plate 2 opposite to the hydrophobic microporous membrane 1, and the interval layer 4 is in contact with the condensation plate 2. The condensing plate 2 is provided with a diversion hole 6, the diversion hole 6 is connected with the fresh water diversion pipeline 8, and the lower drainage hole of the gap layer 4 and the fresh water diversion pipeline 8 are converged by a second control valve 102 and then connected with a fresh water reservoir 10. As shown in fig. 5, the condensation sheet 2 is provided with corrugations 7 on its outer surface.

Example 2

A solar energy and waste heat flat-plate membrane distillation and heat recovery system thereof, as shown in fig. 2, based on the system architecture of embodiment 1. The membrane distillation device is a combined membrane distillation device. The combined membrane distillation device comprises a top membrane distillation unit 14, an intermediate membrane distillation unit 15 and a bottom membrane distillation unit 16, wherein the top membrane distillation unit 14 comprises a hydrophobic microporous membrane 1, a condensation plate 2, a hot seawater flow channel 3, a top gap layer, a cold seawater flow channel 5 and a fresh water diversion channel 8, the top gap layer is arranged between the hydrophobic microporous membrane 1 and the condensation plate 2, the hot seawater flow channel 3 is arranged at the other side of the hydrophobic microporous membrane 1 relative to the condensation plate 2, the cold seawater flow channel 5 is arranged at the other side of the condensation plate 2 relative to the hydrophobic microporous membrane 1, and the top gap layer is in contact with the condensation plate 2. The condensing panels 2 are provided with diversion holes 6, the diversion holes 6 are connected with the fresh water diversion pipeline 8, and the fresh water diversion pipeline 8 is connected with the fresh water reservoir 10 through a fifth control valve 105 and a second pump 112. The top gap layer drain holes communicate with the middle gap layer 151.

The middle-layer membrane distillation unit 15 comprises a hydrophobic microporous membrane 1, a condensing sheet 2, a hot seawater flow channel 3, a middle-layer gap layer and a cold seawater flow channel 5, wherein the middle-layer gap layer is arranged between the hydrophobic microporous membrane 1 and the condensing sheet 2, the hot seawater flow channel 3 is arranged on the other side of the hydrophobic microporous membrane 1 relative to the condensing sheet 2, and the cold seawater flow channel 5 is arranged on the other side of the condensing sheet 2 relative to the hydrophobic microporous membrane 1. The middle gap layer is provided with a middle gap layer liquid drainage hole, and the middle gap layer liquid drainage hole is connected with the water storage tank 10;

the bottom layer membrane distillation unit 16 comprises a hydrophobic microporous membrane 1, a condensation plate 2, a hot seawater flow channel 3, a bottom layer gap layer and a cold seawater flow channel 5, wherein the bottom layer gap layer is arranged between the hydrophobic microporous membrane 1 and the condensation plate 2, the hot seawater flow channel 3 is arranged at the other side of the hydrophobic microporous membrane 1 relative to the condensation plate 2, and the cold seawater flow channel 5 is arranged at the other side of the condensation plate 2 relative to the hydrophobic microporous membrane 1. The fresh water reservoir 10 is connected with a first heat exchanger 131, and the first heat exchanger 131 is connected with the bottom clearance layer through a third pump 113 and a sixth control valve 106; the bottom gap layer is connected to the fresh water reservoir 10 via a seventh control valve 107. And a bottom clearance layer lower drainage hole is arranged below the bottom clearance layer and is connected with the fresh water reservoir 10 through an eighth control valve 108.

As shown in fig. 3 and 4, the combined membrane distillation device comprises a hydrophobic microporous membrane 1 and a condensation sheet 2, wherein one side of the hydrophobic microporous membrane 1 forms a hot seawater flow channel 3, a gap layer 4 is arranged between the hydrophobic microporous membrane 1 and the condensation sheet 2, and the other side of the condensation sheet 2 opposite to the gap layer 4 forms a cold seawater flow channel 5; two partition boards are arranged in the gap layer 4 and are separated from top to bottom into a top gap layer 14, a middle gap layer 15 and a bottom gap layer 16, the partition boards between the top gap layer 14 and the middle gap layer 15 are provided with top gap layer lower drainage holes 26 which are communicated, the top gap layer 14 is provided with top gap layer upper drainage holes 28, the middle gap layer 15 is provided with middle gap layer drainage holes 29, and the bottom gap layer 16 is provided with bottom gap layer upper drainage holes 30.

The hydrophobic microporous membrane 1 and the condensing sheet 2 are arranged in the box body to form the structure, and the upper end of the hot seawater channel 3 is provided with a hot seawater channel inlet 21; a hot seawater channel outlet 22 is provided at the lower end of the hot seawater channel 3. The cold seawater flow channel 5 is sequentially provided with a cold seawater flow channel outlet 24, a fresh water diversion flow channel outlet 25 and a cold seawater flow channel inlet 23 from top to bottom. The condensation plate 2 is provided with two diversion holes 6 on the top gap layer 14, the diversion holes 6 are connected with the fresh water diversion pipeline 8, and the fresh water diversion pipeline 8 is connected with the fresh water diversion pipeline outlet 25.

As shown in fig. 4, the condensation sheet 2 is provided with corrugations 7 on its outer surface.

For the membrane distillation device, in order to verify the optimization effect of the splitter plate on the air gap type membrane distillation device, GAMS (general air purification Modeling System) software is adopted to perform simulation calculation on the air gap type membrane distillation device with the splitting effect, and the calculation result (performance parameters of the device, including energy utilization efficiency and water production rate) is compared with the traditional air gap type membrane distillation device.

The mass transfer and heat transfer processes in the membrane distillation process are complex, and in order to simplify the model, the following assumptions are made in the construction of the mathematical model of membrane distillation: (1) the properties of the membrane such as thickness, tortuosity, porosity, pore diameter and the like are unchanged, and the rejection rate of the membrane is 100 percent; (2) the total pressure difference across the membrane is zero, i.e. there is no viscous flow of mass transfer; (3) the boundary of the membrane distillation device, which is in contact with the external environment, is a heat insulation layer; (4) because the salt concentration of the seawater is low, the physical properties such as specific heat capacity, viscosity and the like of the seawater are the same as those of pure water. The parameters of the membranes used are shown in Table 1-1, the results are shown in Table 1-2, and the water production rate of the split-plate air gap membrane distillation versus the conventional air gap membrane distillation at different feed temperatures is shown in FIG. 6.

TABLE 1-1

Tables 1 to 2

As can be seen from the results of the simulation calculation of the membrane distillation mathematical model in the tables 1-2, the optimization effect of the condensation plate 2 with the shunt holes on the air gap type membrane distillation is mainly embodied in that the water production rate is improved, and in the temperature range of 40-90 ℃, the air gap type membrane distillation adopting 6 shunt plates is 6.3% -26.6% higher than the traditional air gap type membrane distillation in the water production rate; as can be seen from fig. 6, as the feeding temperature gradually increases, the water production rate increasing effect of the splitter plate gradually increases, i.e. under the condition of higher feeding temperature, the splitter plate has a better effect on the increase of the water production rate of the air-gap membrane distillation.

The membrane distillation device, the heating module and the heat recovery module are coupled with each other, and can at least comprise three different operation modes, and the operation modes are adjusted and switched through opening and closing of the control valve. When the membrane distillation device is a combined membrane distillation device, four different operation modes can be included, and the operation modes are adjusted and switched by controlling the opening and closing of a valve.

The three different operation modes of the invention are respectively as follows: the operation under the working condition of sufficient sunlight/high-temperature waste heat is dealt with; the system can be used for dealing with the operation under the working condition of less sunshine/medium-temperature waste heat and dealing with the operation under the working condition of cloudy day or night/low-temperature waste heat.

When the combined membrane distillation device is used, the combined membrane distillation device comprises four different operation modes: the operation under the working condition of sufficient sunshine/high-temperature waste heat is met (a solar energy/waste heat combined type (air gap type-penetrating fluid gap type) membrane distillation heat recovery system and a combined type (air gap type-penetrating fluid gap type-direct contact type) membrane distillation heat recovery system); the system is operated under the working condition of less sunshine/medium temperature waste heat (a solar energy/waste heat combined type (penetrating fluid gap type-penetrating fluid gap type) membrane distillation heat recovery system); the system is suitable for operation under the condition of overcast day or night/low-temperature waste heat (a solar energy/waste heat combined type (penetrating fluid gap type-direct contact type) membrane distillation heat recovery system).

In the heat recovery module, the waste heat of the hot brine after the membrane distillation process is completed is used for preheating cold seawater, and part of the hot brine is mixed with the cold seawater, so that the waste heat of the system is fully utilized, but the material flow ratio of the hot brine to the cold seawater changes along with the change of the temperature of a heat source; meanwhile, the flow rate proportion of the material flow for cooling the condensing plate and the flow rate proportion of the material flow for cooling the circulating fresh water are changed along with the temperature change of the heat source. Therefore, the accurate control of the flow proportion of each control valve is the key for ensuring the efficient and safe operation of the seawater desalination system.

Specifically, the operation mode of the present application is as follows: when the heat source temperature is higher than 70 ℃, the lower outlet flow ratio of the third three-way control valve 123 is 0.6 to 0.9, the right outlet flow ratio of the first three-way control valve 121 is 1, and the left outlet flow ratio of the second three-way control valve 122 is 0.1 to 0.4; when the ambient temperature is lower than 70 ℃ but higher than 50 ℃, the lower outlet flow ratio of the third three-way control valve 123 is 0.3 to 0.6, the right outlet flow ratio of the first three-way control valve 121 is 1, and the left outlet flow ratio of the second three-way control valve 122 is 0.4 to 0.7; when the ambient temperature is lower than 50 c, the lower outlet flow ratio of the third three-way control valve 123 is 0.1 to 0.3, the right outlet flow ratio of the first three-way control valve 121 is 0.7 to 0.9, and the left outlet flow ratio of the second three-way control valve 122 is 1.

When the structure based on the combined membrane distillation device is that, the operation mode of the application is as follows: when the heat source temperature is higher than 70 ℃, the right outlet flow ratio of the third three-way control valve 123 is 0.6 to 0.9, the upper outlet flow ratio of the first three-way control valve 121 is 0.6 to 0.8, and the lower outlet flow ratio of the second three-way control valve 122 is 0.2 to 0.5; when the ambient temperature is lower than 70 ℃ but higher than 50 ℃, the right outlet flow ratio of the third three-way control valve 123 is 0.3 to 0.6, the upper outlet flow ratio of the first three-way control valve 121 is 0.8 to 1, and the lower outlet flow ratio of the second three-way control valve 122 is 0.5 to 0.7; when the ambient temperature is lower than 50 c, the right outlet flow ratio of the third three-way control valve 123 is 0.1 to 0.3, the right outlet flow ratio of the first three-way control valve 121 is 0.7 to 0.9, and the lower outlet flow ratio of the second three-way control valve 122 is 1.

The specific operation mode of the present invention will be described in detail with reference to fig. 1, 2, 7 and 8.

(1) When dealing with sufficient sunlight/high temperature waste heat

When the heat source temperature is higher than 70 ℃: the third control valve 103 and the fourth control valve 104 are in a closed state, the first control valve 101 and the second control valve 102 are in an open state, the first pump 111 and the second pump 112 are in an open state, and the third pump 113 is in a closed state. Seawater logistics process: the cold seawater flows out of the reservoir 9, is supplied with kinetic energy by the first pump 111, and is divided into a first sub-stream S by the first three-way control valve 121₁And a second substream S₂First substream S₁Passes through the first heat exchanger 131 (by the action of the cooling fresh water) and is then discharged from the system, the second substream S₂Then enters the second three-way control valve 122 through the cold seawater flow passage 5 to be divided into a third branch S₃And a fourth substream S₄The fourth substream S₄Direct discharge system, third substream S₃After passing through the regenerator 132, and the sixth branch S₆Converge into a fifth branch S₅Then, howeverThen passes through the third heat exchanger 133, the hot seawater channel 3 and the heat regenerator 132 in sequence, and finally enters the third three-way control valve 123 to be divided into sixth branches S₆And a seventh substream S₇The seventh substream S₇Directly out of the system. The membrane distillation process for producing fresh water: the fifth substream S heated in the third heat exchanger 133₅The mass transfer and heat transfer processes are carried out in the hot seawater flow channel 3 through the hydrophobic microporous membrane 1 and the gap layer 4, the vaporized steam in the hot seawater flow channel 3 passes through the hydrophobic microporous membrane 1 and enters the gap layer 4, and is condensed into fresh water on the contact surface of the gap layer 4 and the condensing plate 2, one part of the condensed fresh water sequentially enters the diversion holes 6 and the fresh water diversion pipeline 8 under the action of the second pump 112, the other part of the condensed fresh water flows out through the lower outlet of the gap layer 4, and the two parts of the condensed fresh water are converged and enter the fresh water reservoir 10. The solar heat collection process comprises the following steps: first cycle working medium S₈Absorbing direct solar heat in the heat collecting pipe 141, and then entering the second heat exchanger 142 for heat exchange, wherein the second cycle working medium S₉The first working fluid S is absorbed in the second heat exchanger 142₈The discharged heat enters the heat storage pool 143 and then enters the third heat exchanger 133 to treat the fifth branch S₅The heat releasing process is performed, and the heat is circulated and repeated through the heat storage tank 143 and the second heat exchanger 142 in sequence.

(2) When dealing with less sunlight/medium temperature waste heat

When the heat source temperature is above 50 ℃ but below 70 ℃: the first control valve 101, the second control valve 102, and the fourth control valve 104 are in a closed state, the third control valve 103 is in an open state, the first pump 111 and the second pump 112 are in an open state, and the third pump 113 is in a closed state. Seawater logistics process: the cold seawater flows out of the reservoir 9, is supplied with kinetic energy by the first pump 111, and is divided into a first sub-stream S by the first three-way control valve 121₁And a second substream S₂First substream S₁Passes through the first heat exchanger 131 (by the action of the cooling fresh water) and is then discharged from the system, the second substream S₂Then enters the second three-way control valve 122 through the cold seawater flow passage 5 to be divided into a third branch S₃And a fourth substream S₄The fourth substream S₄The waste water is directly discharged out of the system,third substream S₃After passing through the regenerator 132, and the sixth branch S₆Converge into a fifth branch S₅Then passes through the third heat exchanger 133, the hot seawater channel 3 and the heat regenerator 132 in sequence, and finally enters the three-way control valve 123 to be divided into sixth branches S₆And a seventh substream S₇The seventh substream S₇Directly out of the system. The membrane distillation process for producing fresh water: the fifth substream S heated in the third heat exchanger 133₅The mass transfer and heat transfer processes are carried out in the hot seawater flow channel 3 through the hydrophobic microporous membrane 1 and the gap layer 4, the vaporized steam in the hot seawater flow channel 3 passes through the hydrophobic microporous membrane 1 and enters the gap layer 4, the vaporized steam is condensed into fresh water in the gap layer 4, the condensed fresh water is continuously accumulated in the gap layer 4 until overflowing, and the overflowing condensed fresh water flows into the fresh water reservoir 10 through the opened third control valve 103. The solar heat collection process comprises the following steps: first cycle working medium S₈Absorbing direct solar heat in the heat collecting pipe 141, and then entering the second heat exchanger 142 for heat exchange, wherein the second cycle working medium S₉The first working fluid S is absorbed in the second heat exchanger 142₈The discharged heat enters the heat storage pool 143 and then enters the third heat exchanger 133 to treat the fifth branch S₅The heat releasing process is performed, and the heat is circulated and repeated through the heat storage tank 143 and the second heat exchanger 142 in sequence.

(3) Coping with the waste heat in cloudy days or at night/low temperature

When the temperature of the heat source is lower than 50 ℃: the second control valve 102 and the third control valve 103 are in a closed state, the first control valve 101 and the fourth control valve 104 are in a closed state, the first pump 111 and the third pump 113 are in an open state, and the second pump 112 is in a closed state. Seawater logistics process: the cold seawater flows out of the reservoir 9, is supplied with kinetic energy by the first pump 111, and is divided into a first sub-stream S by the first three-way control valve 121₁And a second substream S₂First substream S₁Passes through the first heat exchanger 131 (by the action of the cooling fresh water) and is then discharged from the system, the second substream S₂Enters the bean three-way control valve 122 through the cold seawater channel 5 and is divided into a third branch S₃And a fourth substream S₄The fourth substream S₄Direct discharge system, third branchStream S₃After passing through the regenerator 132, and the sixth branch S₆Converge into a fifth branch S₅Then passes through the third heat exchanger 133, the hot seawater channel 3 and the heat regenerator 132 in sequence, and finally enters the third three-way control valve 123 to be divided into sixth branches S₆And a seventh substream S₇The seventh substream S₇Directly out of the system. The membrane distillation process for producing fresh water: the fifth substream S heated in the third heat exchanger 133₅The mass transfer and heat transfer processes are carried out through the hydrophobic microporous membrane 1 and the gap layer 4 in the hot seawater flow channel 3, the vaporized steam in the hot seawater flow channel 3 passes through the hydrophobic microporous membrane 1 and enters the gap layer 4, and is condensed into fresh water in the gap layer 4, the fresh water in the fresh water reservoir 12 passes through the first heat exchanger 131 under the action of the third pump 113, then enters the gap layer 4 for the heat exchange process, and then is gathered with the condensed fresh water and enters the fresh water reservoir 10. A standby heat source heating process: the working medium in the heat storage pool 143 is heated by the standby heat source 144, and the working medium enters the third heat exchanger 133 after being heated to carry out heat treatment on the fifth branch S₅The heat release process is performed, and then the heat is returned to the heat storage pool 143 to be circulated.

(4) When dealing with sufficient sunlight/high temperature waste heat

When the heat source temperature is higher than 70 ℃: in the system shown in fig. 2, the seventh control valve 107 and the ninth control valve 109 are in a closed state, the fifth control valve 105, the sixth control valve 106, and the eighth control valve 108 are in an open state, the first pump 111 and the second pump 112 are in an open state, and the third pump 113 is in a closed state. Seawater logistics process: the cold seawater flows out of the reservoir 11, is supplied with kinetic energy by the first pump 111, and is divided into a first sub-stream S by the first three-way control valve 121₁And a second substream S₂First substream S₁Passes through the first heat exchanger 131 (by the action of the cooling fresh water) and then exits the system, the first substream S₂Passes through the cold seawater channel 5 and then enters the second three-way control valve 122 to be divided into a third branch S₃And a fourth substream S₄The fourth substream S₄Direct discharge system, third substream S₃After passing through the regenerator 132, and the sixth branch S₆Converge into a fifth branch S₅Of 1 atFive tributaries S₅Passes through the third heat exchanger 133, the hot seawater channel 13 and the heat regenerator 132 in sequence, and finally enters the third three-way control valve 123 to be divided into sixth branches S₆And a seventh substream S₇The seventh substream S₇Directly out of the system. The membrane distillation process for producing fresh water: the fifth substream S heated by the third heat exchanger 133₅The mass transfer and heat transfer processes are carried out in the hot seawater flow channel 3 through the hydrophobic microporous membrane 1 and the gap layer; the vaporized steam in the hot seawater flow channel 3 passes through the hydrophobic microporous membrane 1 and enters the top gap layer, the middle gap layer and the bottom gap layer; the permeating steam in the top gap layer is condensed into fresh water on the contact surface of the condensing plate 2, one part of the condensed fresh water sequentially enters the diversion holes 6 and the fresh water diversion pipeline 8 under the action of the pump 112, and the other part of the condensed fresh water flows into the middle gap layer through the lower drainage holes 26 of the top gap layer; the penetrating steam in the middle gap layer is subjected to contact heat exchange with condensed water or the condensing plate 2 to be condensed into fresh water, and the condensed fresh water is continuously accumulated in the middle gap layer until overflowing from the liquid discharge hole 29 of the middle gap layer; the permeating steam in the bottom gap layer is condensed into fresh water through contact heat exchange with the condensed water or the condensing plate 2, the condensed fresh water is continuously accumulated in the bottom gap layer until overflowing from the drainage holes 30 on the bottom gap layer, and finally the three parts of condensed fresh water are collected into the fresh water reservoir 10. The solar heat collection process comprises the following steps: first cycle working medium S₈Absorbing direct solar heat in the heat collecting pipe 141, then entering the heat exchanger 142 for heat exchange, and using a second cycle working medium S₉The first working fluid S is absorbed in the heat exchanger 142₈The discharged heat enters the heat storage pool 143 and then enters the third heat exchanger 133 to treat the fifth branch S₅The heat releasing process is performed, and the heat is circulated and reciprocated through the heat storage tank 143 and the heat exchanger 142 in sequence.

(5) Dealing with sufficient sunlight/high temperature waste heat

When the heat source temperature is higher than 70 ℃: in the system shown in fig. 2, the eighth control valve 108 is in a closed state, the fifth control valve 105, the sixth control valve 106, the seventh control valve 107, and the fifth control valve 109 are in an open state, and the first pump 111, the second pump 112, and the third pump 113 are in an open state. Seawater logistics process: the cold seawater flows out of the reservoir 9, is supplied with kinetic energy by the first pump 111, and is divided into a first sub-stream S by the first three-way control valve 121₁And a second substream S₂First substream S₁Passes through the first heat exchanger 131 (by the action of the cooling fresh water) and is then discharged from the system, the second substream S₂Passes through the cold seawater channel 5 and then enters the second three-way control valve 122 to be divided into a third branch S₃And a fourth substream S₄The fourth substream S₄Direct discharge system, third substream S₃After passing through the regenerator 132, and the sixth branch S₆Converge into a fifth branch S₅Fifth substream S₅Passes through the third heat exchanger 133, the hot seawater channel 3 and the heat regenerator 132 in sequence, and finally enters the third three-way control valve 123 to be divided into sixth branches S₆And a seventh substream S₇The seventh substream S₇Directly out of the system. The membrane distillation process for producing fresh water: the fifth substream S heated by the third heat exchanger 133₅The mass transfer and heat transfer processes are carried out in the hot seawater flow channel 3 through the hydrophobic microporous membrane 11 and the gap layer; the vaporized steam in the hot seawater flow channel 3 passes through the hydrophobic microporous membrane 1 and enters the top gap layer, the middle gap layer and the bottom gap layer; the permeating steam in the top gap layer is condensed into fresh water on the contact surface of the condensing plate 2, one part of the condensed fresh water sequentially enters the diversion holes 6 and the fresh water diversion pipeline 8 under the action of the second pump 112, and the other part of the condensed fresh water flows into the middle gap layer through the lower drainage holes 26 of the top gap layer; the penetrating steam in the middle gap layer is subjected to contact heat exchange with condensed water or the condensing plate 2 to condense into fresh water, the condensed fresh water is continuously accumulated in the middle gap layer until overflowing from the liquid discharge hole 29 of the middle gap layer, and the two parts of condensed fresh water are converged into the fresh water reservoir 10; the circulating fresh water flows out of the fresh water reservoir 10 under the action of the third pump 113, sequentially passes through the first heat exchanger 131, the third pump 113 and the opened seventh control valve 107, then enters the bottom interstitial layer, the permeated steam in the bottom interstitial layer is condensed into fresh water through heat exchange with the circulating fresh water, and the condensed fresh water and the circulating fresh water flow out of the drainage holes 27 in the bottom interstitial layer and then enter the fresh water reservoir 10. Solar energyAnd (3) heat collection process: first cycle working medium S₈Absorbing direct solar heat in the heat collecting pipe 141, then entering the heat exchanger 142 for heat exchange, and using a second cycle working medium S₉The first working fluid S is absorbed in the heat exchanger 142₈The discharged heat enters the heat storage pool 143 and then enters the third heat exchanger 133 to treat the fifth branch S₅The heat releasing process is performed, and the heat is circulated and reciprocated through the heat storage tank 143 and the heat exchanger 142 in sequence.

(6) When dealing with less sunlight/medium temperature waste heat

When the heat source temperature is above 50 ℃ but below 70 ℃: in the system shown in fig. 2, the fifth control valve 105, the sixth control valve 106, the seventh control valve 107, and the ninth control valve 109 are in a closed state, the eighth control valve 108 is in an open state, the first pump 111 is in an open state, and the second pump 112 and the third pump 113 are in a closed state. Seawater logistics process: the cold seawater flows out of the reservoir 9, is supplied with kinetic energy by the first pump 111, and is divided into a first sub-stream S by the first three-way control valve 121₁And a second substream S₂First substream S₁Passes through the first heat exchanger 131 (by the action of the cooling fresh water) and is then discharged from the system, the second substream S₂Passes through the cold seawater channel 17 and then enters the second three-way control valve 122 to be divided into a third branch S₃And a fourth substream S₄The fourth substream S₄Direct discharge system, third substream S₃After passing through the regenerator 132, and the sixth branch S₆Converge into a fifth branch S₅Fifth substream S₅Passes through the third heat exchanger 133, the hot seawater channel 3 and the heat regenerator 132 in sequence, and finally enters the three-way control valve 123 to be divided into sixth branches S₆And a seventh substream S₇The seventh substream S₇Directly out of the system. The membrane distillation process for producing fresh water: the fifth substream S heated by the heat exchanger 133₅The mass transfer and heat transfer processes are carried out in the hot seawater flow channel 13 through the hydrophobic microporous membrane 1 and the three gap layers; the vaporized steam in the hot seawater flow channel 3 passes through the hydrophobic microporous membrane 1 and enters the top gap layer, the middle gap layer and the bottom gap layer; the penetrating steam in the top gap layer is condensed into condensed water through contact heat exchange with condensed water or a condensing plate 2Fresh water, the condensed fresh water, continues to accumulate in the top gap layer until overflowing from the drainage holes 28 in the top gap layer; the penetrating steam in the middle gap layer 151 is condensed into fresh water through contact heat exchange with condensed water or the condensing plate 2, and the condensed fresh water is continuously accumulated in the middle gap layer until overflowing from the drain holes 26 in the top gap layer to enter the top gap layer and overflowing from the drain holes 28 in the top gap layer together with the condensed fresh water accumulated in the top gap layer; the permeating steam in the bottom gap layer is condensed into fresh water through contact heat exchange with the condensed water or the condensing plate 2, the condensed fresh water is continuously accumulated in the bottom gap layer until overflowing from the drainage holes 30 on the bottom gap layer, and finally the three parts of condensed fresh water are collected into the fresh water reservoir 10. The solar heat collection process comprises the following steps: first cycle working medium S₈Absorbing direct solar heat in the heat collecting pipe 141, then entering the heat exchanger 142 for heat exchange, and using a second cycle working medium S₉The first working fluid S is absorbed in the heat exchanger 142₈The discharged heat enters a heat storage pool 143 and then enters a heat exchanger 133 to treat the fifth branch S₅The heat releasing process is performed, and the heat is circulated and reciprocated through the heat storage tank 143 and the heat exchanger 142 in sequence.

(7) Coping with the waste heat in cloudy days or at night/low temperature

When the temperature of the heat source is lower than 50 ℃: in the system shown in fig. 2, the fifth control valve 105, the sixth control valve 106, and the eighth control valve 108 are in a closed state, the seventh control valve 107, and the ninth control valve 109 are in an open state, the first pump 111, and the third pump 113 are in an open state, and the second pump 112 is in a closed state. Seawater logistics process: the cold seawater flows out of the reservoir 9, is supplied with kinetic energy by the first pump 111, and is divided into a first sub-stream S by the first three-way control valve 121₁And a second substream S₂First substream S₁Passes through the first heat exchanger 131 (by the action of the cooling fresh water) and is then discharged from the system, the second substream S₂Passes through the cold seawater channel 5 and then enters the three-way control valve 122 to be divided into a third branch S₃And a fourth substream S₄The fourth substream S₄Direct discharge system, third substream S₃After passing through the regenerator 132, and the sixth branch S₆Converge into a fifth branch S₅Fifth substream S₅Passes through the third heat exchanger 133, the hot seawater channel 3 and the heat regenerator 132 in sequence, and finally enters the three-way control valve 123 to be divided into S₆And a seventh substream S₇The seventh substream S₇Directly out of the system. The membrane distillation process for producing fresh water: the fifth substream S heated by the heat exchanger 133₅The mass transfer and heat transfer processes are carried out in the hot seawater flow channel 3 through the hydrophobic microporous membrane and the three clearance layers; the vaporized steam in the hot seawater flow channel 3 passes through the hydrophobic microporous membrane 1 and enters the top gap layer, the middle gap layer and the bottom gap layer; the penetrating steam in the top gap layer is condensed into fresh water through contact heat exchange with condensed water or the condensing plate 2, and the condensed fresh water is continuously accumulated in the top gap layer until overflowing from the drainage hole 28 on the top gap layer; the permeating steam in the middle gap layer is subjected to contact heat exchange with condensed water or the condensing plate pieces 2 to be condensed into fresh water, the condensed fresh water is continuously accumulated in the middle gap layer until the condensed fresh water overflows from the drainage holes 26 in the top gap layer and enters the top gap layer, and the condensed fresh water accumulated in the top gap layer overflow from the drainage holes 28 in the top gap layer, and the two parts of condensed fresh water are converged and enter the fresh water reservoir 10; the circulating fresh water flows out of the fresh water reservoir 10 under the action of the third pump 113, sequentially passes through the first heat exchanger 131, the third pump 113 and the opened seventh control valve 107, then enters the bottom interstitial layer, the permeated steam in the bottom interstitial layer is condensed into fresh water through heat exchange with the circulating fresh water, and the condensed fresh water and the circulating fresh water flow out of the drainage holes 27 in the bottom interstitial layer and then enter the fresh water reservoir 10. A standby heat source heating process: and the working medium in the heat storage tank 143 is heated by the standby heat source 144, and the working medium enters the third heat exchanger 133 after being heated to release heat of the fifth branch stream S5, and then returns to the heat storage tank 143 to circulate.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.