CN107720863A - A kind of groove type solar sea water desalinating unit based on film distillation - Google Patents

Abstract

The invention discloses a kind of groove type solar sea water desalinating unit based on film distillation for belonging to field of seawater desalination.Exist for current main-stream desalination with Solar Energy (such as flash distillation of solar energy multiple-effect evaporation, solar energy multi-stage, solar energy reverse osmosis) and invest the limitations such as high, solar thermal utilization rate is not high, system and device efficiency is low, the solar energy that heat energy needed for sea water by distillation is launched from Trough Concentrating System in the present invention.Solar energy reflection is focused on the circular arc thermal-collecting tube in membrane module, to the heating of seawater of Bottomhole pressure.After seawater is heated in thermal-collecting tube, hydrophobic distillation film both sides form steam pressure difference due to the temperature difference be present in membrane module.Due to the effect of both sides differential pressure of membrane, the moisture in seawater will pass through hydrophobic membrane pores in vapour form, and water vapor stream is formed in another wing passage of hydrophobic membrane.Water vapour condensation finally be can obtain into liquid fresh water, be collected in fresh water tank.

Description

A trough solar seawater desalination device based on membrane distillation

technical field

The invention belongs to the field of seawater desalination, in particular to a trough solar seawater desalination device based on membrane distillation.

Background technique

Seawater desalination technology is essentially a technology to separate the salt and water in seawater through certain physical, chemical or physicochemical processes with the help of specific devices and equipment. The specific operation is to take fresh water from seawater, or to remove the salt in seawater to obtain fresh water. Nowadays, thermal method and membrane method have become two important mainstream technical methods of seawater desalination technology, and multi-stage flash evaporation, low-temperature multi-effect distillation and compressed air distillation are the three main methods of thermal seawater desalination. Although the multi-stage flash evaporation technology is mature and reliable and does not require seawater pretreatment, it has high requirements on the operating temperature of the system, high energy consumption, complicated process procedures, and large equipment investment. Low-temperature multiple-effect distillation has the advantages of low operating temperature and simple pretreatment, but the equipment structure is complicated and the investment is large. However, the power consumption of the compressed air distillation method is high, and the cost is also very large. The three main methods of membrane seawater desalination are reverse osmosis, electrodialysis and membrane distillation. The reverse osmosis method has the advantages of good separation effect, wide application range, and simple equipment, but the membrane components are easily damaged and the operating cost is high, while the energy consumption of electrodialysis is too high and the effect is not good. Membrane distillation has the advantages of high rejection rate, low operating temperature, simple equipment structure, and the ability to treat high-concentration wastewater.

The world's energy crisis and water resource scarcity are becoming more and more serious, seawater desalination technology has become a hot spot in current research, but using conventional energy for seawater desalination not only has high investment costs, but also aggravates energy shortages. Therefore, the use of renewable clean energy, such as solar energy, to achieve seawater desalination will become an important direction for the development of seawater desalination technology.

At the same time, the current mainstream solar desalination technology (such as solar multi-effect evaporation, solar multi-stage flash evaporation, solar reverse osmosis, etc.) has limitations such as high investment, low solar thermal utilization rate, serious pollutant discharge, and low system device efficiency. Facing the problems of high energy consumption and low quality of produced water by osmotic membrane method.

Contents of the invention

The purpose of the present invention is to overcome the existing problems in the existing seawater desalination, and provides a trough-type solar seawater desalination device based on membrane distillation, which is characterized in that it includes: a heat collection and purification device, a condenser, a freshwater collection tank, seawater Valves, circulation pumps, expanders and generators; the heat collection and purification device includes membrane modules; the seawater inlet of the condenser communicates with natural seawater through pipes; the seawater outlet of the condenser is connected to the heat collection and purification device through seawater valves and circulation pumps The seawater inlet pipeline on the left side below the membrane module, the concentrated seawater outlet on the right side below the membrane module are connected to the water inlet valve of the expander, the water outlet valve of the expander is connected to the outside world, and the generator is connected to the expander to absorb the water transmitted by the expander. The external power output, the power input of the circulating pump is connected to the power output of the generator and the external power grid; the fresh water vapor outlet pipe on the left above the membrane module is connected to the inlet of the cooling coil in the condenser, and flows into the bottom of the membrane module through the seawater inlet pipe Part of the seawater is converted into water vapor in the membrane module and discharged from the fresh water vapor outlet pipe, and the remaining concentrated seawater is discharged from the concentrated seawater outlet; the outlet of the cooling coil in the condenser is connected to the fresh water collection tank, and the condenser uses seawater as The cooling medium is driven into the heat collecting tube by the circulation pump.

The heat collection and purification device includes: a membrane assembly, a trough parabolic reflector, two receiver brackets, a small reflector support frame, a large reflector support frame and a reflector support shaft, wherein the small reflector support frame and the large reflector support The supporting frames are arranged parallel to each other on the horizontal ground, and the two ends of the supporting shaft of the transmitting mirror are respectively connected with the top of the supporting frame of the small transmitting mirror and the top of the supporting frame of the large transmitting mirror, and the trough type parabolic reflector is installed on the supporting shaft of the transmitting mirror; The upper and lower ends of the root receiver bracket are respectively connected with the supporting shaft of the emitting mirror and the membrane assembly; wherein the arc side of the arc-shaped heat collecting tube in the membrane assembly faces the trough parabolic reflector.

Preferably, the height of the support frame of the small reflector is smaller than the height of the support frame of the large reflector.

The membrane module includes: a water vapor pipeline, a hydrophobic distillation membrane, an arc-shaped heat collection tube, a fresh water steam outlet pipe, a seawater inlet pipeline and a concentrated seawater outlet, wherein the hydrophobic distillation membrane is installed in the membrane module, and the membrane module is divided into upper The two parts of the water vapor pipe and the arc-shaped heat collecting tube below, the upper and lower sides of the hydrophobic distillation membrane form a steam pressure difference due to the temperature difference; the water in the seawater passes through the pores in the hydrophobic distillation membrane in the form of steam due to the pressure difference. The water vapor flow is formed in the water vapor pipe on the other side of the hydrophobic distillation membrane; the water vapor pipe is a metal tube with a grooved or arc-shaped cross-section, and the arc-shaped heat collecting tube is a double-layer pipe with an arc-shaped or D-shaped cross-section. Among them, the inner tube of the arc-shaped heat collecting tube is a metal tube, and seawater flows through the tube; the outer tube is a glass tube, and the vacuum is drawn between the outer tube and the inner tube. The heat collecting tube provides heat energy for the membrane module, and heats the seawater flowing in the arc-shaped heat collecting tube; the water vapor pipe and the pipe wall of the arc-shaped heat collecting tube are fixedly connected, and the two ends are aligned, and the seawater inlet pipe and the concentrated seawater outlet are respectively It is installed outside the left and right ends of the arc-shaped heat collecting pipe, and the fresh water vapor outlet pipe is installed outside the left end of the water vapor pipe, and is located on the same side of the membrane module as the seawater inlet pipe.

The hydrophobic distillation membrane is a polymer hydrophobic microporous distillation membrane.

The inner tube of the arc-shaped heat collecting tube is coated with a selective absorption coating, wherein the selective absorption coating is copper oxide, black nickel, black chrome, black zinc, black copper.

The fresh water vapor outlet pipe and the small mirror support frame are located on the same side of the heat collection and purification device.

The electric energy required by the circulation pump is generated by a generator or input by an external power grid.

A kind of fresh water purification workflow of a trough solar seawater desalination device based on membrane distillation, characterized in that, under the action of a circulating pump, seawater is transported from the condenser to the arc-shaped heat collecting tube below the membrane module; after that The seawater is heated and pressurized under the action of the trough-type parabolic mirror, and a pressure difference is formed between the upper and lower sides of the distillation membrane due to the temperature difference. Under the action of the pressure difference, the water in the lower seawater passes through the hydrophobic pores of the hydrophobic distillation membrane in the form of steam to obtain water vapor; the water vapor enters the cooling coil in the condenser from the steam pipe of the membrane module, and is absorbed by the lower temperature The seawater condenses to form fresh water, and finally the fresh water collected by the cooling coil is collected into the fresh water collection tank; the distilled concentrated seawater is discharged from the concentrated seawater outlet on the right side of the arc-shaped heat collecting tube to the expander, and then the expanded The external power drives the generator to generate electricity.

The beneficial effects of the present invention are:

1. The present invention combines the advantages of thermal seawater desalination and membrane seawater desalination, directly uses the trough solar collector to heat the seawater, and the heated seawater undergoes membrane distillation in the membrane module to obtain fresh water vapor, and finally condenses the fresh water vapor Get liquid fresh water.

2. In addition to using solar energy, this device can basically achieve zero energy consumption in the seawater desalination process, and effectively develops and utilizes the thermal film coupled seawater desalination technology of renewable clean energy solar energy, making energy utilization more reasonable and effective;

3. The device has small investment, low energy consumption, simple structure, easy maintenance, strong applicability, high-quality water production, and has broad prospects for sustainable development.

Description of drawings

Fig. 1 is the connection and flow diagram of the embodiment of a trough-type solar seawater desalination device based on membrane distillation of the present invention;

Fig. 2 is the structural representation of heat collecting and purifying device in the embodiment;

Fig. 3 is the structural representation of membrane module in the embodiment;

In the figure: 103-condenser, 104-fresh water collection tank, 105-sea water valve, 106-circulation pump, 107-expander, 108-generator, 201-membrane module, 202-trough parabolic mirror, 203-two Root receiver bracket, 204-small launch mirror support frame, 205-large launch mirror support frame, 206-transmitter mirror support shaft, 301-water vapor pipeline, 302-hydrophobic distillation film, 303-arc heat collecting tube, 304- Fresh water steam outlet pipe, 305-seawater inlet pipeline, 306-concentrated seawater outlet.

detailed description

The present invention provides a trough-type solar seawater desalination device based on membrane distillation, and the specific implementation of the present invention will be described below with reference to the accompanying drawings.

As shown in Figure 1, a trough solar desalination device based on membrane distillation of the present invention consists of a membrane module 201, a trough parabolic mirror 202, a fresh water vapor outlet pipe 304, a seawater inlet pipeline 305, a concentrated seawater outlet 306, Condenser 103, fresh water collecting tank 104, seawater valve 105, circulating pump 106, expander 107 and generator 108 are made up; Wherein the seawater inlet of condenser 103 communicates with natural seawater through pipeline; The seawater outlet of 103 passes seawater valve 105 and circulation The pump 106 is connected to the seawater inlet pipeline 305 on the left side below the membrane module 201, the concentrated seawater outlet 306 on the right side below the membrane module 201 is connected to the water inlet valve of the expander 107, and the water outlet valve of the expander 107 is connected to the outside world; Machine 107 is driven to do work by the concentrated seawater discharged from concentrated seawater outlet 306, generator 108 is connected with expander 107 to absorb the external work transmitted by expander 107, and the power output of generator 108 is connected with the power input of circulation pump 106; The electric energy required by 106 can be input through an external power grid, or can be obtained by coaxially driving the generator 108 with the expander 107 to generate electricity. The fresh water vapor outlet pipe 304 on the left side above the membrane module 201 is connected to the inlet of the cooling coil in the condenser 103, and the seawater below the membrane module 201 flows into the seawater from the seawater inlet pipeline 305, and part of it is converted into a water vapor flow in the membrane module 201 It is discharged from the fresh water vapor outlet pipe 304, and the remaining concentrated seawater is discharged from the concentrated seawater outlet 306. The outlet of the cooling coil in the condenser 103 is connected with the fresh water collection tank 104. The condenser 103 uses seawater as a cooling medium and is driven into the Heat collecting tube; the arc side of the lower part of the membrane module 201 faces the trough parabolic reflector 202, and the trough type concentrating reflector 202 focuses the solar energy reflection on the arc heat collecting tube 303 in the membrane module 201. The seawater flowing in the heat collecting tube 303 is heated to provide heat energy required for seawater distillation;

The working process of fresh water purification in this embodiment is as follows: under the action of circulation pump 106, seawater is transported from condenser 103 to the arc-shaped heat collecting tube 303 below membrane module 102; It is heated and pressurized under the action, and a pressure difference is formed between the upper and lower sides of the distillation membrane 302 due to the temperature difference. Under the effect of pressure difference, the moisture in the seawater on the lower side (high temperature side) permeates the hydrophobic pores of the hydrophobic distillation membrane 302 in the form of steam, thereby obtaining water vapor; The coil is condensed by seawater with a lower temperature to form fresh water, and finally the fresh water collected by the cooling coil is collected in the fresh water collection tank 104; the distilled concentrated seawater is discharged from the concentrated seawater outlet 306 on the right side of the arc-shaped heat collecting tube 303 to the expander 107, and then the external work transmitted by the expander 107 drives the generator 108 to generate electricity; the electric energy required by the circulation pump 106 is generated by the generator 108 or input from an external grid.

As shown in Figure 2, the heat collecting and purifying device comprises: a membrane assembly 201, a trough parabolic reflector 202, two receiver brackets 203, a small reflector support frame 204, a large reflector support frame 205 and a reflector support shaft 206, Wherein the small mirror support frame 204 and the large mirror support frame 205 are parallel to each other and are arranged on the level ground, and the two ends of the mirror support shaft 206 are respectively connected with the top of the small mirror support frame 204 and the top of the large mirror support frame 205 , the reflector support shaft 206 forms a certain angle with the horizontal plane, the trough parabolic reflector 202 is installed on the reflector support shaft 206, and the trough parabolic reflector 202 can surround the reflector support shaft 206 according to the system working environment and actual requirements Rotate, the height of the small reflector support frame 204<the height of the large reflector support frame 205, so that the trough parabolic reflector 202 and the membrane module 201 are at a certain angle of inclination with the horizontal plane, and the water vapor and the fresh water condensed in advance can be naturally Flow into the condenser 103; the upper and lower ends of the two receiver brackets 203 are respectively connected with the reflector support shaft 206 and the membrane assembly 201; wherein the arc side of the arc-shaped heat collecting tube 303 in the membrane assembly 201 faces the trough parabolic reflector 202.

As shown in Figure 3, the membrane assembly 201 is composed of a steam pipe 301, a distillation membrane 302, an arc-shaped heat collection pipe 303, a fresh water vapor outlet pipe 304, a seawater inlet pipeline 305 and a concentrated seawater outlet 306, wherein the distillation membrane 302 is a high The molecular hydrophobic microporous distillation membrane is installed in the membrane module 201. The membrane module 201 is divided into two parts: the upper water vapor pipe 301 and the lower arc-shaped heat collection tube 303. The upper and lower sides of the hydrophobic distillation membrane 302 form steam due to the temperature difference. Pressure difference; the moisture in the seawater passes through the pores in the hydrophobic distillation membrane 302 in the form of steam due to the pressure difference, and forms a water vapor flow in the water vapor pipeline 301 on the other side of the hydrophobic distillation membrane 302; the water vapor pipeline 301 has a cross-section of Grooved or arc-shaped metal tubes, arc-shaped heat collecting tubes 303 are double-layer tubes with arc-shaped or D-shaped cross-sections, in which the inner tube is made of metal tubes, and seawater flows through the tubes, and the inner tubes are coated with selective absorption coatings (such as copper oxide, black nickel, black chromium, black zinc, black copper, etc.), the outer tube is a glass tube, and the vacuum is drawn between the outer tube and the inner tube. The arc-shaped heat collecting tube 303 in the middle provides heat energy for the membrane module 201, and heats the seawater flowing in the arc-shaped heat collecting tube 303; The seawater inlet pipe 305 and the concentrated seawater outlet 306 are respectively installed outside the left and right ends of the arc-shaped heat collecting pipe 303, and the fresh water vapor outlet pipe 304 is installed outside the left end of the water vapor pipe 301, and the seawater inlet pipe 305 is located outside the membrane module 201. same side.

Claims (9)

1. A kind of 1. groove type solar sea water desalinating unit based on film distillation, it is characterised in that including：Thermal-arrest purifier, Condenser (103), fresh water collecting tank (104), seawater valve (105), circulating pump (106), expanding machine (107) and generator (108)；The seawater inlet of condenser (103) is communicated by pipeline with nature seawater；The seawer outlet of condenser (103) passes through sea Penstock (105) and circulating pump (106) are connected to the seawater inlet pipeline of membrane module (201) lower left in thermal-arrest purifier (305), the concentrated seawater outlet (306) of membrane module (201) lower right is connected with the water intaking valve of expanding machine (107), expanding machine (107) outlet valve is connected with the external world, and generator (108) is connected what is spread out of to absorb expanding machine (107) with expanding machine (107) External work, the electric power input of circulating pump (106) are connected with the electric power output and external electrical network of generator (108)；On membrane module (201) The fresh water steam outlet pipe (304) in side left side is connected with the entrance of cooling coil in condenser (103), by seawater inlet pipeline (305) seawater flowed into below membrane module (201), is partly converted into vapor stream by fresh water steam in membrane module (201) Outlet (304) is discharged, and remaining concentrated seawater exports (306) by concentrated seawater and discharged；The outlet of cooling coil in condenser (103) Be connected with fresh water collecting tank (104), condenser (103) uses seawater as cooling medium, and by circulating pump (106) drive into Enter thermal-collecting tube.
2. A kind of 2. groove type solar sea water desalinating unit based on film distillation according to claim 1, it is characterised in that institute Stating thermal-arrest purifier includes：Membrane module (201), groove type parabolic mirror (202), two receiver holders (203), small hairs Mirror support frame (204), big transmitting mirror support frame (205) and transmitting mirror support shaft (206) are penetrated, its medium and small transmitting mirror support frame (204) and big transmitting mirror support frame (205) is arranged in parallel on level ground, and the both ends of transmitting mirror support shaft (206) are divided It is not connected with the top of small transmitting mirror support frame (204) and the top of big transmitting mirror support frame (205), groove type parabolic mirror (202) it is installed in transmitting mirror support shaft (206)；The upper and lower ends of two receiver holders (203) support with transmitting mirror respectively Axle (206) and membrane module (201) connection；The circular arc side of circular arc thermal-collecting tube (303) is thrown to slot type wherein in membrane module (201) Parabolic mirror (202).
3. A kind of 3. groove type solar sea water desalinating unit based on film distillation according to claim 2, it is characterised in that institute State the height of big transmitting mirror support frame (205) described in the height ＜ of small transmitting mirror support frame (204).
4. A kind of 4. groove type solar sea water desalinating unit based on film distillation according to claim 1, it is characterised in that institute Stating membrane module (201) includes：Water vapour pipeline (301), hydrophobic distillation film (302), circular arc thermal-collecting tube (303), fresh water steam Outlet (304), seawater inlet pipeline (305) and concentrated seawater outlet (306), wherein hydrophobic distillation film (302) is installed on film group In part (201), membrane module (201) is divided into the water vapour pipeline (301) of top and the circular arc thermal-collecting tube (303) two of lower section Point, the both sides up and down of hydrophobic distillation film (302) are due to temperature difference formation steam pressure difference；Moisture in seawater is because of the effect steam of pressure difference Form is through the hole in hydrophobic distillation film (302), in water vapour pipeline (301) interior shape of hydrophobic distillation film (302) opposite side Into water vapor stream；Water vapour pipeline (301) is that section is for groove type or the metal tube of arc, circular arc thermal-collecting tube (303) Section is arc or the bimetallic tube of D-shaped, and the wherein inner tube of circular arc thermal-collecting tube (303) is metal tube, and seawater is walked in pipe；Outer tube is Glass tube, vacuumized between outer tube and inner tube, solar energy reflection is focused on membrane module (201) by Trough Concentrating System (202) In circular arc thermal-collecting tube (303) provide heat energy for membrane module (201), the seawater of flowing in circular arc thermal-collecting tube (303) is entered Row heating；The tube wall of water vapour pipeline (301) and circular arc thermal-collecting tube (303) is affixed, both ends alignment, seawater inlet pipeline (305) installed respectively outside the left and right ends with circular arc thermal-collecting tube (303) with concentrated seawater outlet (306), fresh water steam outlet pipe (304) it is installed on outside the left end of water vapour pipeline (301), is located at membrane module (201) homonymy with seawater inlet pipeline (305).
5. A kind of 5. groove type solar sea water desalinating unit based on film distillation according to claim 4, it is characterised in that：Institute It is that high molecular hydrophobic micropore distills film to state hydrophobic distillation film (302).
6. A kind of 6. groove type solar sea water desalinating unit based on film distillation according to claim 4, it is characterised in that：Institute State and coating for selective absorption scribbled outside the inner tube of circular arc thermal-collecting tube (303), wherein coating for selective absorption be cupric oxide, it is black Nickel, black chromium, black zinc, black copper.
7. 7. according to a kind of one of claim 2 or 4 groove type solar sea water desalinating unit based on film distillation, its feature It is, the fresh water steam outlet pipe (304) and the small transmitting mirror support frame (204) are located at the homonymy of thermal-arrest purifier.
8. 8. according to a kind of one of claim 2 or 4 groove type solar sea water desalinating unit based on film distillation, its feature It is, the electric energy needed for the circulating pump (106) is produced by generator (108) or inputted by external electrical network.
9. A kind of 9. purged with fresh water workflow of the groove type solar sea water desalinating unit based on film distillation described in claim 1 Journey, it is characterised in that in the presence of circulating pump (106), seawater is transported to from condenser (103) under membrane module (102) In the circular arc thermal-collecting tube (303) of side；Seawater is heated and boosted in the presence of groove type parabolic mirror (202) afterwards, Because the temperature difference makes distillation film (302), both sides form pressure difference up and down.Under differential pressure action, the moisture in the seawater of downside is in vapour form Through the hydrophobic pores of hydrophobic distillation film (302), so as to obtain water vapour；Water vapour is entered by the jet chimney of membrane module (102) Enter the cooling coil in condenser (103), by the relatively low seawater condensing of temperature, form fresh water, finally gather cooling coil Fresh water be concentrated to fresh water collecting tank (104)；Concentrated seawater outlet of the concentrated seawater on the right side of circular arc thermal-collecting tube (303) after distillation (306) expanding machine (107) is expelled to, the external work that subsequent expanding machine (107) is spread out of drives generator (108) to produce electric power.