CN111777246B

CN111777246B - Low-temperature multi-effect distillation method and SSCC membrane method seawater desalination system

Info

Publication number: CN111777246B
Application number: CN202010552472.3A
Authority: CN
Inventors: 孙嘉琦; 孙嘉保禄; 孙成
Original assignee: WENZHOU HAIDENENG ENVIRONMENTAL PROTECTION EQUIPMENT & TECHNOLOGY CO LTD
Current assignee: WENZHOU HAIDENENG ENVIRONMENTAL PROTECTION EQUIPMENT & TECHNOLOGY CO LTD
Priority date: 2020-06-17
Filing date: 2020-06-17
Publication date: 2022-04-26
Anticipated expiration: 2040-06-17
Also published as: CN111777246A

Abstract

The invention discloses a low-temperature multi-effect distillation method and a seawater desalination system adopting an SSCC membrane method, which at least comprise a bearing plate, a multi-effect evaporator and a light-transmitting condensation cover, wherein the multi-effect evaporator and the light-transmitting condensation cover are arranged on the bearing plate to form a closed first evaporation cavity in a surrounding mode, the multi-effect evaporator is provided with at least one second evaporation cavity, the water vapor in the first evaporation cavity and the light-transmitting condensation cover carry out heat exchange to convert the water vapor into condensed water, and the water vapor can also carry out heat exchange with the multi-effect evaporator under the condition that the condensed water flows along the light-transmitting condensation cover based on the weight of the condensed water to enter the second evaporation cavity, so that the condensed water in the second evaporation cavity is heated again to form the water vapor. Through the vapor of printing opacity condensation cover and multi-effect evaporator in to the first evaporation chamber simultaneously cooling to can accelerate the condensation process of vapor, in for example sunshine sufficient season, can avoid vapor to pile up, and then can reach the technological effect who improves solar energy utilization ratio and sea water desalination water yield.

Description

Low-temperature multi-effect distillation method and SSCC membrane method seawater desalination system

Technical Field

The invention belongs to the technical field of seawater desalination equipment, and particularly relates to a low-temperature multi-effect distillation method and an SSCC membrane method seawater desalination system.

Background

With the sustainable and stable development of economy in China, the demand of various industries on water resources is increasing. Because the rainfall in China changes obviously along with seasons and regions, and the demand for industrial water rises year by year, water resources in certain regions, particularly east coastal regions are seriously short, the economic loss caused each year reaches hundreds of billions of yuan, and the water resource crisis seriously restricts the economic development of China. In order to deal with the water source crisis, except for the planned implementation of water storage and water transfer engineering and the popularization of water saving technology, the seawater desalination technology is developed, and the extraction of fresh water from the ocean is an effective way for solving the fresh water demand of China, particularly coastal areas.

At present, the commercial seawater desalination method at home and abroad mainly comprises multi-stage flash evaporation, low-temperature multi-effect distillation, vapor compression distillation and reverse osmosis technology. The low-temperature multi-effect distillation is a seawater desalination technology with the highest evaporation temperature of salt water of about 70 ℃, and is characterized in that a series of evaporators are connected in series and divided into a plurality of effect groups, secondary steam generated by evaporation in a former effect evaporator is used as heating steam of a latter effect evaporator, distilled water with the amount being multiple times of the amount of the heating steam is obtained through multiple times of evaporation and condensation, and the low-temperature multi-effect distillation has the advantages of simple pretreatment, high water yield ratio, good water quality and the like, and can be developed rapidly in China in recent years. But the low-temperature multi-effect distillation desalination needs to consume a large amount of commodity steam, and the popularization and application of the low-temperature multi-effect distillation desalination are limited by the price of the steam to a great extent.

The prior art is disclosed in patent document No. CN106145227A, which discloses a low-temperature multi-effect seawater desalination system and a desalination method, wherein before raw materials enter a low-temperature multi-effect distillation system, when the temperature of the raw materials is lower than the set temperature of the materials entering an end-effect evaporator, the raw materials are preheated by a concentrated seawater heat exchanger so as to reach the preset value when the raw materials enter the evaporator; the concentrated water of the evaporator of the former effect group enters the evaporator of the former effect group after exchanging heat with the concentrated water recovered by the evaporator of the first effect group through the concentrated water heat exchanger by adopting the feeding of the effect component sections. The problem of low seawater recovery rate of materials in the traditional parallel feeding process can be solved, and the operation dosing and power consumption cost is reduced; not only overcomes the defects of the traditional process mode, but also improves the thermal efficiency of the low-temperature multi-effect desalination system and reduces the equipment investment and the operation cost; the technological process has the advantages of high water making ratio, high material water recovering rate, low power consumption, high heat efficiency, low equipment investment, low running cost, etc.

Disclosure of Invention

The invention aims to provide a low-temperature multi-effect distillation method and an SSCC membrane method seawater desalination system which have the advantages of high water production rate, self-cleaning of a filter membrane and energy conservation.

The technical scheme adopted by the invention for realizing the purpose is as follows: low temperature multiple effect distillation method and SSCC embrane method sea water desalination system, at least including accepting the board, multi-effect evaporator and printing opacity condensation cover all set up on accepting the board in order to enclose into the first evaporation chamber that is the confined form, multi-effect evaporator has at least one second evaporation chamber, vapor in first evaporation chamber carries out the heat exchange with printing opacity condensation cover and changes into the comdenstion water, and the comdenstion water is based on its self weight and flows in order to get into under the condition in second evaporation chamber along printing opacity condensation cover, vapor can also carry out the heat exchange with multi-effect evaporator and make the comdenstion water in the second evaporation chamber heated once more and form vapor. The multi-effect evaporator at least comprises a first water collecting tank and a plurality of evaporation plates, each evaporation plate is in a hollow cylindrical shape, and the inner diameters of the evaporation plates are different from each other, so that the evaporation plates can be arranged in a layer-by-layer nested mode to form a second evaporation cavity, the first water collecting tank is arranged on the end portion of each evaporation plate to seal the second evaporation cavity, each evaporation plate is provided with a first surface close to the first evaporation cavity and a second surface far away from the first evaporation cavity, water vapor in the first evaporation cavity can exchange heat with the first surface of the evaporation plate with the smallest inner diameter, and under the condition that condensed water in the first water collecting tank enters the second evaporation cavity in a flowing mode along the second surface of the evaporation plate with the smallest inner diameter, the condensed water can be heated again to form the water vapor. Through the vapor of printing opacity condensation cover and multi-effect evaporator in to the first evaporation chamber simultaneously cooling to can accelerate the condensation process of vapor, in for example sunshine sufficient season, can avoid vapor to pile up, and then can reach the technological effect who improves solar energy utilization ratio and sea water desalination water yield.

The bearing plate is further provided with a filtering part and a second water collecting tank, a second evaporation cavity is communicated with the second water collecting tank through the filtering part, the filtering part at least comprises a shell, a first filtering membrane and a cleaning body, at least two first filtering membranes are arranged in the shell to separate an inner cavity of the shell into a second cavity, a third cavity and a first cavity located between the first filtering membranes, and the cleaning body is arranged in the first cavity, wherein the density of the cleaning body is greater than that of water, condensed water in the second evaporation cavity can enter the first cavity from the bottom of the first cavity to impact the cleaning body, so that the cleaning body can move and is abutted against and contacted with the first filtering membrane in the moving process. The self-cleaning of the filtering membrane can be realized by arranging the cleaning body, and the replacement frequency of the filtering membrane can be further reduced.

The bearing plate is also provided with a circulating power part, and both the second water collecting tank and the filtering part can be coupled to the circulating power part, so that under the condition that condensed water enters the second water collecting tank to increase the whole weight of the second water collecting tank, the second water collecting tank can trigger the circulating power part to work to increase or decrease the distance between the first filtering membranes in a mode of changing the bending forms of the first filtering membranes. The circulating power part at least comprises a fixed frame, an elastic body, a flexible air bag and a sliding block, the fixed frame is arranged on the bearing plate, the sliding block is connected to the fixed frame in a sliding mode, the elastic body is connected to the first side of the sliding block, the flexible air bag is connected to the second side of the sliding block, the flexible air bag can be communicated with the shell, and under the condition that the weight of the second water collecting tank is increased, the sliding block can extrude the flexible air bag according to the stretching elastic body, so that gas in the flexible air bag can be injected into the shell. The flexible airbag can be communicated with the first cavity through the first channel, the second cavity and the third cavity can be communicated with the flexible airbag through the second channel, and the first channel and the second channel can be in a state of being periodically and alternately opened. The distance between the first filter membranes can be increased when gas in the flexible bladder enters the first cavity through the first passage, or the distance between the first filter membranes can be decreased when gas in the flexible bladder enters the second cavity and/or the third cavity through the second passage. When the flexible air bag periodically injects gas into the first cavity, the second cavity and the third cavity, the pressure of the first cavity, the second cavity and the third cavity can be reduced, so that the first filtering membrane can be bent in a left-right swinging mode, and the accumulation degree of dirt on the first filtering membrane can be reduced. And when the distance between the first filtering membranes is reduced and the first filtering membranes are in a concave shape, the contact degree between the cleaning body and the first filtering membranes can be increased, so that the scraping and cleaning effect of the cleaning body on the first filtering membranes is enhanced. When the gas is injected into the first cavity, the flow of the cleaning body can be accelerated, and the scraping effect of the cleaning body on the first filtering membrane is further enhanced.

The sliding block is also provided with an annular wing plate, the bearing plate floats on the sea surface, and when the sea surface fluctuates and fluctuates up and down, seawater impacts the wing plate, so that the wing plate can drive the sliding block to move up and down. The wing plate can drive the sliding block to move. Namely, the wave energy can be fully utilized, so that the aim of reducing energy consumption is fulfilled.

The bearing plate is also provided with an exhaust passage communicated with the first cavity, the second cavity and the third cavity, so that gas in the first cavity, the second cavity and the third cavity can enter the first evaporation cavity. The end part of the exhaust channel is also provided with a plurality of nozzles positioned in the first evaporation cavity, and the nozzles are obliquely arranged so as to form an included angle of less than 90 degrees with the evaporation plate. When gas is from the nozzle blowout, it can strike vapor, and then can drive vapor and lean on the contact with evaporating plate or printing opacity condensation cover with faster speed, and then shorten vapor's condensation time, finally reach the purpose that improves the water yield.

The invention adopts the circulating power part, the nozzle and the cleaning body, thereby having the following beneficial effects: 1. through the vapor of printing opacity condensation cover and multi-effect evaporator in to the first evaporation chamber simultaneously cooling to can accelerate the condensation process of vapor, in for example sunshine sufficient season, can avoid vapor to pile up, and then can reach the technological effect who improves solar energy utilization ratio and sea water desalination water yield. 2. The cleaning body can move and is in abutting contact with the first filtering membrane during the moving process. The self-cleaning of the filtering membrane can be realized by arranging the cleaning body, and the replacement frequency of the filtering membrane can be further reduced. 3. When gas is from the nozzle blowout, it can strike vapor, and then can drive vapor and lean on the contact with evaporating plate or printing opacity condensation cover with faster speed, and then shorten vapor's condensation time, finally reach the purpose that improves the water yield. Therefore, the invention is an energy-saving compressor with high water yield, self-cleaning filtering membrane and energy saving.

Drawings

FIG. 1 is a schematic diagram of a seawater desalination system using a low-temperature multi-effect distillation method and an SSCC membrane method;

FIG. 2 is a schematic view of a curved configuration of the first filter membrane after the distance between the first filter membranes has been reduced;

FIG. 3 is a schematic view of a curved configuration with an increased distance between the first filter membranes;

FIG. 4 is a schematic structural view of the circulating power section;

FIG. 5 is a schematic view of the arrangement of the second filtering membrane.

Reference numerals: the solar panel comprises a bearing plate 1, a multi-effect evaporator 2, a light-transmitting condensation cover 3, a first evaporation cavity 4, a first water collecting tank 2a, an evaporation plate 2b, a second evaporation cavity 5, a first end part 6, a second end part 7, a first accommodating area 8, a second accommodating area 9, a first plate body 10, a second plate body 11, a third plate body 12, a first surface 13, a second surface 14, a circulating power part 15, a filtering part 16, a second water collecting tank 17, a fixed frame 15a, an elastic body 15b, a flexible air bag 15c, a sliding block 15d, a first side 18, a second side 19, a shell 16a, a first filtering membrane 16b, a second filtering membrane 16c, a cleaning body 16d, a first cavity 20, a second cavity 21, a third cavity 22, a water discharging pipe 23, a first channel 24, a second channel 25, an exhaust channel 26, a nozzle 27, an included angle alpha and a wing plate 28.

Detailed Description

The technical solution of the present invention is further described in detail below with reference to the following detailed description and the accompanying drawings:

example 1:

as shown in fig. 1 to 5, the present application provides a seawater desalination system by low-temperature multi-effect distillation and SSCC membrane method, which at least comprises a receiving plate 1, a multi-effect evaporator 2 and a light-transmitting condensation cover 3. A partial area of the receiving plate 1 may be made of foam or foam may be provided thereon to enable the seawater desalination system to float on the sea surface based on the buoyancy generated by the receiving plate 1. The multi-effect evaporator 2 and the light-transmitting condensation cover 3 are both arranged on the bearing plate 1. The bearing plate 1, the multi-effect evaporator 2 and the light-transmitting condensation cover 3 can jointly form a closed first evaporation cavity 4. Specifically, the multiple-effect evaporator 2 at least comprises a first water collection tank 2a and a plurality of evaporation plates 2 b. The evaporation plate 2b may have a hollow cylindrical shape. The inner or outer diameter of each evaporation plate 2b is different from each other, so that the evaporation plates 2b can be arranged in a nested manner with each other, and finally a second evaporation cavity 5 can be formed between two adjacent evaporation plates 2 b. That is, the first end 6 of the evaporation plate 2b may be connected to the socket plate 1. The second end 7 of the evaporation plate 2b may be provided with a first header tank 2 a. The second evaporation chamber 5 can be brought into a sealed state by the sealing of the receiving plate 1 and the first header tank 2 a. The light-transmitting condensation cover 3 can be connected to the first water collection tank 2a so that condensed water droplets on the light-transmitting condensation cover 3 can flow along the light-transmitting condensation cover 3 to enter the first water collection tank 2a based on its own weight. The first header tank 2a may also communicate with the second evaporation chamber 5 so that the condensed water in the first header tank 2a can flow along the surface of the evaporation plate 2b based on its own weight. For example, a siphon string may be provided on the evaporation plate 2 b. The siphon rope may be made of cotton. And then after the one end of siphon rope inserted in first water catch tank 2a, the comdenstion water in first water catch tank 2a just can flow along the siphon rope (the siphon rope can be similar to the wick of kerosene lamp promptly). The receiving plate 1 or the transparent condensing cover 3 can be provided with a heat absorption film to absorb solar energy, so that seawater in the first evaporation cavity 4 can be heated to generate water vapor. The generated water vapor can contact with the light-transmitting condensation cover 3 and the evaporation plate 2b with the smallest inner diameter, so that heat exchange is formed, and the water vapor is cooled to form condensed water. The condensed water on the light-transmitting condensation cover 3 can enter the first water collection tank 2 a.

The receiving plate 1 has at least a first receiving area 8 for receiving seawater and a second receiving area 9 for receiving condensate. The first receiving area 8 and the second receiving area 9 are independent of each other. I.e. in a disconnected state. The condensed water formed after contacting with the evaporation plate 2b having the smallest inner diameter can enter the second containing area 9 and a drain pipe can be arranged on the second containing area 9 to drain the condensed water in time. Specifically, as shown in fig. 1, the present invention may have three evaporation plates 2 b. For convenience of description, the inner diameters are named as a first plate body 10, a second plate body 11 and a third plate body 12 from small to large, respectively. The second evaporation chamber 5 will be formed between the first plate body 10 and the second plate body 11 and between the second plate body 11 and the third plate body 12. The first, second and

third plate bodies

10, 11, 12 each have a first surface 13 and a second surface 14. The water vapour in the first evaporation chamber 4 can be in contact with the first surface 13 of the first plate body 10. When the condensed water in the first header tank 2a flows from the second surface 14 of the first plate body 10, the condensed water can be evaporated into water vapor again during the flow. That is, condensed water will form on the first surface 13 of the first plate body 10 and enter the second receiving area 9, and water vapor will form on the second surface 14 of the first plate body 10. The water vapour formed by the second surface 14 of the first plate body 10 will come into contact with the first surface 13 of the second plate body 11 to form water condensate and the water condensate flowing along the second surface 14 of the second plate body 11 is heated to form water vapour. The low-temperature multi-effect evaporation is formed through the process. Meanwhile, the condensate water in the first water collecting tank 2a is evaporated again through the multi-effect evaporator 2, so that the salinity in the condensate water can be further removed.

The low-temperature multi-effect distillation method and SSCC membrane method seawater desalination system also comprises a circulating power part 15, a filtering part 16 and a second water collecting tank 17. The second evaporation chamber 5 can communicate with the second header tank 2a so that the condensed water in the second evaporation chamber 5 enters the second header tank 17. Both the circulation power section 15 and the filter section 16 can be connected to the socket plate 1. The second header tank 17 can be coupled with the circulation power part 15 so that the circulation power part 15 can be triggered to operate when the condensed water enters the second header tank 17 such that the entire weight of the second header tank 17 is increased. The filter part 16 can be coupled with the circulation power part 15 so that the pressure inside the filter part 16 can be increased to improve the filtering efficiency of the filter part 16. Specifically, the circulating power section 15 includes at least a fixed frame 15a, an elastic body 15b, a flexible bladder 15c, and a slider 15 d. The fixing frame 15a may be provided on the bearing plate 1. The slider 15d is slidably provided on the fixed frame 15 a. For example, the fixed frame 15a may be provided with a sliding groove, and the slider 15d may be nested in the sliding groove so as to be slidable along the sliding groove. The resilient body 15b may be a compression spring which is arranged on the first side 18 of the slider 15 d. The flexible bladder 15c is disposed on the second side 19 of the slider 15 d. The second header tank 17 may be connected to the slider 15d by a connection rope 20. When the weight of the second water collecting tank 17 increases, it can be pulled to move the slider 15d downward, at which time the elastic body 15b will be stretched and the flexible air bag 15c will be compressed so that the gas inside thereof can be discharged. When the weight of the second water collecting tank 17 is too low, the slider 15d moves upward by the elastic potential energy of the elastic body 15b, so that the flexible air 15c is restored to the original state.

The filter portion 16 includes at least a housing 16a, a first filter membrane 16b, a second filter membrane 16c, and a cleaning body 16 d. At least two first filter membranes 16a are disposed in the housing 16a to divide the internal cavity of the housing 16a into a first cavity 20, a second cavity 21, and a third cavity 22. The area between the two first filter membranes 16a is the first cavity 20. The second and

third cavities

21 and 22 are located on both sides of the first cavity 20. The second evaporation chamber 5 can be communicated with the first chamber 20, so that the condensed water in the second evaporation chamber 5 can enter the first chamber 20. The condensed water in the first cavity 20 can enter the second cavity 21 and/or the third cavity 22 after being filtered by the first filtering membrane 16 c. The second and

third chambers

21 and 22 can each communicate with the second header tank 17 through a drain pipe 23, wherein the second filtering membrane 16c is disposed in the drain pipe 23. The cleaning body 16d is disposed in the first cavity 20. The density of the cleaning body 16d is greater than that of water. A water pump can be arranged between the second evaporation cavity 5 and the first cavity 20, so that condensed water can be sprayed into the first cavity 20 at a certain pressure to impact the cleaning body 16d, and finally the cleaning body 16d can flow. During the flowing of the cleaning body 16d, it can scrape the surface of the first filter membrane 16b, and can remove dirt on the surface of the first filter membrane 16 b. The first filtration membrane 16b may be an SSRO reverse osmosis membrane and the second filtration membrane 16c may be a CCUF ultrafiltration membrane. And the seawater sequentially passes through the first filtering membrane and the second filtering membrane to form a process of treating the seawater by an SSCC membrane method.

The flexible bladder 15c can communicate with the first cavity 20 via the first channel 24. The second and

third cavities

21, 22 can communicate with the flexible bladder 15c via a second passageway 25. Independent valves may be provided in each of the first and

second passages

24, 25 to enable manual or automatic control of the respective open states of the first and

second passages

24, 25. For example, during a first set time period, the first passage 24 is opened and the second passage 25 is closed, so that the exhaust gas in the flexible bladder 15c can enter the first chamber 20, and at this time, the pressure in the first chamber 20 will increase, so that the filtering efficiency of the first filtering membrane 16b is increased. Meanwhile, the gas entering the first cavity 20 can further drive the cleaning body 16d to flow, so as to achieve the purpose of improving the cleaning effect of the first filtering membrane 16 b. During a second set time period, the first passage 24 is closed and the second passage 25 is opened to allow the exhaust gas from the flexible bladder 15c to enter the second chamber 21 and/or the third chamber 22.

The first filter membrane 16b can assume a curved configuration based on a pressure differential between the first and

second cavities

20, 21 or a pressure differential between the first and

third cavities

20, 22. For example, when the gas in the flexible bladder 15c is injected into the first chamber 20, the first filter membrane 16b will bend toward the second chamber 21 or the third chamber 22, and the distance between the two first filter membranes 16b will increase. When the gas in the flexible bladder 15c is injected into the second cavity 21 or the third cavity 22, the first filter membrane 16b will bend towards the first cavity 20, and the distance between the two first filter membranes 16b will decrease. When the distance between the first filter membranes 16b is decreased, the degree of contact of the cleaning bodies 16d with the first filter membranes 16b will be increased, and the scraping action of the cleaning bodies 16b on the first filter membranes 16b can be increased.

The first evaporation cavity 4 can be formed by communicating the first cavity 20, the second cavity 21 and the third cavity 22, so that the gas in the first cavity 20, the second cavity 21 and the third cavity 22 can enter the first evaporation cavity 4. Specifically, the receiving plate 1 is provided with an exhaust passage 26. The exhaust channel 26 has several nozzles 27 located in the first evaporation chamber 4. The nozzles can be arranged obliquely so that the nozzles 27 can form an angle α of less than 90 ° with the evaporating plate 2 b. For example, the nozzle 27 may be inclined toward the side of the evaporation plate 2b, so that the gas sprayed from the nozzle 2b can drive the water vapor to move to contact the light-transmitting condensation cover 3 or the first plate 10 in a rapid abutting manner, thereby achieving rapid condensation.

The slider 15d is provided with a circular wing plate 28. Under the condition of sea surface wave fluctuation, seawater can impact the wing plate 28, so that the wing plate 28 drives the slider 15d to move up and down along with the sea surface wave fluctuation, and thus, gas is continuously injected into at least one of the first cavity 20, the second cavity 21 and the third cavity 22. The flexible bladder 15c may be provided with an air inlet valve so that air can be sucked into the flexible bladder 15c when it returns to its original state.

Claims

1. A seawater desalination system adopting a low-temperature multi-effect distillation method and an SSCC membrane method at least comprises a bearing plate (1), a multi-effect evaporator (2) and a light-transmitting condensation cover (3), it is characterized in that the multi-effect evaporator (2) and the light-transmitting condensation cover (3) are both arranged on the bearing plate (1) to form a closed first evaporation cavity (4) in a surrounding way, the multi-effect evaporator (2) is provided with at least one second evaporation cavity (5), the water vapor in the first evaporation cavity (4) exchanges heat with the light-transmitting condensation cover (3) to be converted into condensed water, and the condensed water flows along the light-transmitting condensation cover (3) based on its own weight to enter the second evaporation cavity (5), the water vapor can also exchange heat with the multi-effect evaporator (2) to ensure that the condensed water in the second evaporation cavity (5) is heated again to form water vapor;

the bearing plate (1) is further provided with a filtering part (16) and a second water collecting tank (17), the second evaporation cavity (5) is communicated with the second water collecting tank (17) through the filtering part (16), the filtering part (16) at least comprises a shell (16a), a first filtering membrane (16b) and a cleaning body (16d), at least two first filtering membranes (16b) are arranged in the shell (16a) to divide an inner cavity of the shell (16a) into a second cavity (21), a third cavity (22) and a first cavity (20) positioned between the first filtering membranes (16b), the cleaning body (16d) is arranged in the first cavity (20), wherein the density of the cleaning body (16d) is greater than that of water, condensed water in the second evaporation cavity (5) can enter the first cavity (20) from the bottom of the first cavity (20) to impact the cleaning body (16d), enabling the cleaning body (16d) to move and to come into abutting contact with the first filter membrane (16b) during the movement;

the bearing plate (1) is also provided with a circulating power part (15), the second water collecting tank (17) and the filtering part (16) can be coupled to the circulating power part (15), so that in the case that condensed water enters the second water collecting tank (17) to increase the overall weight of the second water collecting tank (17), the second water collecting tank (17) can trigger the circulating power part (15) to work to increase or decrease the distance between the first filtering membranes (16b) in a mode of changing the bending form of the first filtering membranes (16 b);

the circulating power part (15) at least comprises a fixed frame (15a), an elastic body (15b), a flexible air bag (15c) and a sliding block (15d), the fixed frame (15a) is arranged on the bearing plate (1), the sliding block (15d) is connected to the fixed frame (15a) in a sliding mode, the elastic body (15b) is connected to a first side (18) of the sliding block (15d), the flexible air bag (15c) is connected to a second side (19) of the sliding block (15d), the flexible air bag (15c) can be communicated with the shell (16a), and under the condition that the weight of the second water collecting tank (17) is increased, the sliding block (15d) can extrude the flexible air bag (15c) according to the stretching of the elastic body (15b) so that the gas in the flexible air bag (15c) can be injected into the shell (16 a);

the flexible bladder (15c) being communicable with the first cavity (20) via a first channel (24), the second cavity (21) and the third cavity (22) being communicable with the flexible bladder (15c) via a second channel (25), wherein the first channel (24) and the second channel (25) are capable of being in a periodically alternately opened state;

the bearing plate (1) is further provided with an exhaust channel (26) communicated with the first cavity (20), the second cavity (21) and the third cavity (22), so that gas in the first cavity (20), the second cavity (21) and the third cavity (22) can enter the first evaporation cavity (4).

2. The cryogenic multi-effect distillation and SSCC membrane process seawater desalination system as claimed in claim 1, wherein the multi-effect evaporator (2) comprises at least a first water collection tank (2a) and a plurality of evaporation plates (2b), each evaporation plate (2b) is hollow cylindrical, and the respective inner diameters of each evaporation plate (2b) are different from each other, so that the plurality of evaporation plates (2b) can be arranged in a layer-by-layer nested manner to form the second evaporation cavity (5), the first water collection tank (2a) is arranged on the end of the evaporation plate (2b) to seal the second evaporation cavity (5), wherein each evaporation plate (2b) has a first surface (13) close to the first evaporation cavity (4) and a second surface (14) far away from the first evaporation cavity (4), and the water vapor in the first evaporation cavity (4) can enter the first surface (13) of the evaporation plate (2b) with the smallest inner diameter And performing heat exchange so that the condensed water can be heated again to form water vapor under the condition that the condensed water in the first water collecting tank (2a) enters the second evaporation cavity (5) along the second surface (14) of the evaporation plate (2b) with the smallest inner diameter.

3. The system for desalinating seawater according to claim 1, wherein the distance between the first filtering membranes (16b) can be increased when the gas in the flexible bladder (15c) enters the first cavity (20) through the first channel (24), or the distance between the first filtering membranes (16b) can be decreased when the gas in the flexible bladder (15c) enters the second cavity (21) and/or the third cavity (22) through the second channel (25).

4. The system for desalinating seawater according to the low-temperature multi-effect distillation method and the SSCC membrane method as claimed in claim 1, wherein the sliding block (15d) is further provided with an annular wing plate (28), and when the bearing plate (1) floats on the sea surface and fluctuates up and down due to the fluctuation of the sea surface, seawater impacts the wing plate (28), so that the wing plate (28) can drive the sliding block (15d) to move up and down.

5. The system for desalinating seawater according to claim 1, wherein the end of the exhaust channel (26) is further provided with a plurality of nozzles (27) located in the first evaporation chamber (4), and the nozzles (27) are arranged in an inclined manner so as to form an included angle (α) smaller than 90 ° with the evaporation plate (2 b).