CN104528853A - Double-chimney embedded type solar seawater desalination system and desalination method thereof - Google Patents

Abstract

The invention discloses a built-in double-chimney solar seawater desalination system and a desalination method thereof. A horizontally arranged heat collection shed is connected to the inner chimney; an obliquely arranged linear Fresnel type light concentrating heat collector is connected to the outer chimney; The height of the chimney is higher than that of the inner chimney; there is a wind turbine at the bottom of the inner chimney; there is a liquid separator in the partition wall of the inner and outer chimneys; and a condenser is arranged in the outer chimney. The solar-heated horizontal heat collection shed generates air flow; the air flow pushes the wind turbine at the bottom of the inner chimney to provide part of the power required by the system; the linear Fresnel-type concentrator heats seawater to generate water vapor; the air flow in the inner chimney The injected water vapor flows to the condenser and condenses into fresh water; the fresh water flows into the fresh water tank along the outer chimney wall; the higher temperature brine flows into the heat storage layer at the bottom of the horizontal heat collection shed to store energy. The invention has a compact structure, rationally separates the power source and the energy source, can better utilize and manage solar energy, and improves fresh water production rate.

Description

An embedded double-chimney solar seawater desalination system and its desalination method

technical field

The invention belongs to the technical field of seawater desalination, and relates to a solar thermal seawater desalination method, in particular to a solar seawater desalination system and a desalination method with embedded double chimneys.

Background technique

China's per capita freshwater resources are about 2200m ³ , which is a quarter of the world's average level, and is listed by the United Nations as one of the thirteen most water-deficient countries. Our country is a big ocean country with a long coastline, and we can use solar energy to desalinate seawater. There are more than 20 types of solar desalination technologies, and there are two main methods: one is to use solar power to drive the reverse osmosis process; the other is to use solar energy to generate heat to distill seawater to make it evaporate through phase change. The solar reverse osmosis method requires high-pressure pumps, reverse osmosis membranes, heat exchangers, condensers and other components, so the system is complex and the initial investment cost is high. The solar distillation method is simple, widely used, mature technology, and does not require additional power input.

In 1982, Dr. Schlaich of the University of Stuttgart in Germany designed and built the first solar chimney demonstration power station. The turbine generator set at the connection part is composed of three main components, among which the height of the chimney is 194.6m, the radius of the chimney is 5.08m, the area of the heat collecting shed is 46000m ² , and the theoretical power generation is 50kW. Its working process is that sunlight irradiates the heat-collecting shed, heating the air in the shed and the soil under the shed, the temperature of the heated air rises, the density decreases, and a strong updraft is formed under the suction of the solar chimney to drive the wind turbine to generate electricity At the same time, the cold air around the heat collecting shed is supplemented into the shed to form a continuous air circulation. Existing studies have shown that the electrical efficiency of solar thermal airflow power generation systems is extremely low, and the electrical efficiency of MW-level power stations is only 1%. However, the thermal efficiency of the system is relatively high, generally reaching more than 50%.

Combining the solar chimney system with the desalination of seawater by solar distillation, and using the heat energy obtained from the sun to evaporate seawater will give full play to the advantages of both, and has the advantages of simple structure and high efficiency. There have been cases of combining solar chimney system with solar distillation seawater desalination in the existing patents, respectively: the announcement number CN1331764C, the announcement date is August 15, 2007 and the publication number is CN101358578A, the announcement date is February 4, 2009 Japan's Chinese invention patent. However, in these patents, the brine pool is directly arranged under the heat collection shed. When the solar energy heats the heat collection shed, a large amount of energy will be consumed in the evaporation of brine, thereby losing a lot of energy, and at the same time reducing the change in the density of the steam in the heat collection shed. , thereby affecting the airflow velocity into the chimney and reducing the freshwater production rate.

Contents of the invention

In order to overcome the deficiencies of the prior art above, the technical problem to be solved by the present invention is to provide a new type of seawater desalination system based on solar chimneys, which uses solar energy to provide energy source and power source respectively. Specifically: the energy source is mainly used to concentrate light to heat seawater to evaporate it, and the power source is mainly to heat the air to generate high-speed flowing airflow in the chimney. The evaporated steam and updraft enter the built-in solar chimney and are cooled by the condenser. freshwater. At the same time, the present invention also introduces preheating, energy recovery and thermal storage systems.

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

A built-in double-chimney solar desalination system, including inner chimney (1), outer chimney (2), linear Fresnel concentrator (3), transparent heat collection shed (5), seawater preheating Condenser (6), condenser (7), seawater input pipe (8), water receiving tank (10), fresh water tank (11), heat absorbing plate on the bottom of heat collecting shed (12), concentrated seawater heat storage tank (13) , support group (17), fresh water connecting pipe (18); the inner chimney (1) is embedded in the outer chimney (2), and a seawater preheater (6) is arranged below the outlet of the inner chimney (1), and the outer chimney ( 2) A built-in condenser (7); the bottom of the inner chimney (1) is connected to a transparent heat collection shed (5), and a water receiving tank (10) is provided at the connection, and the water receiving tank (10) is connected by fresh water The pipe (18) is connected to the fresh water tank (11), and the bottom of the transparent heat-collecting shed (5) is supported by multiple sets of support groups (17), and the support groups (17) are located on the heat-absorbing plate on the bottom of the heat-collecting shed ( 12), the upper end of the support group (17) is also obliquely provided with a linear Fresnel-type concentrating heat collector (3), and a concentrated seawater heat storage tank is provided under the heat-absorbing plate (12) on the bottom of the heat-collecting shed (13), a horizontal seawater input pipe (8) is arranged below the concentrated seawater heat storage tank (13).

A wind turbine (4) is arranged at the bottom of the inner chimney (1).

The above-mentioned linear Fresnel type concentrating heat collector (3) is composed of a Fresnel lens (19) and a blackened heat-absorbing surface (20), and the Fresnel lens (19) is smaller than the blackened heat-absorbing surface (20). )Width.

The above-mentioned blackened heat-absorbing surface (20) adopts black paint and is stepped.

A seawater circumferential liquid separator (9) is arranged inside the outer chimney (2), and the seawater circumferential liquid separator (9) is connected to the blackened heat-absorbing surface (20).

The fresh water tank (11) is horizontally provided with a fresh water output pipe (15), and the concentrated seawater heat storage tank (13) is horizontally provided with a concentrated seawater output pipe (16).

The above-mentioned condenser (7) is higher than the outlet of the inner chimney (1), and is arranged obliquely and symmetrically.

The above-mentioned transparent heat collecting shed (5) is provided with vents (14).

A method for desalination of seawater with built-in double-chimney solar energy, using the above-mentioned system, includes the following steps:

(1) After primary filtration, the seawater is pumped to the seawater preheater (6), where it exchanges heat with the external wet steam to increase the temperature, and then slowly flows into the coating from the seawater circumferential liquid pipe (9). On the black heat-absorbing surface (20), a seawater liquid film is formed on the heat-absorbing surface, so that the Fresnel lens (19) concentrates and heats the black heat-absorbing surface (20), and then evaporates the seawater film above the heat-absorbing surface , water vapor is generated, and the concentrated seawater flows into the concentrated seawater tank (13), where heat energy is accumulated for use when there is no sun, and the concentrated seawater tank is filled with water and flows out from the concentrated seawater output pipe (16);

(2), the air is divided into two paths, one path flows in from the linear Fresnel concentrating heat collector (3), and the other path enters from between the transparent heat collecting shed (5) and the heat absorbing plate (12) on the bottom surface of the heat collecting shed In the inner chimney (1), in the linear Fresnel concentrator (3), the air is blown from above the seawater film, and the air humidity increases greatly when the seawater film evaporates rapidly, and the moist air is affected by the buoyancy force and the inner chimney (1) Under the action of jet ejection, it enters the inner and outer chimney walls, and then flows to the seawater preheater (6), where the humid air flow space suddenly increases and the action of the seawater preheater (6) condenses into fresh water dripping into the The lower water receiving tank (10) is then stored in the fresh water tank (11); between the transparent heat collecting shed (5) and the heat absorbing plate (12) on the bottom of the heat collecting shed, when the air flows through the transparent heat collecting shed (5) It is heated, so that the temperature rises and the density decreases, and enters the inner chimney (1) under the action of chimney buoyancy, and then flows to the outer chimney (2).

(3) In the outer chimney (2), it is mixed with the humid air passing through the seawater preheater (6) and enters the condenser (7), where it continues to condense part of the steam and then discharges it into the atmosphere;

(4) The wind turbine (4) is reserved for peak regulation; the electric energy obtained by wind power is stored in the battery after frequency modulation by the inverter, and then the pump is driven to make seawater flow into the seawater input pipe (8). If there is surplus electric energy It can be directly used as an electrically heated seawater film or a concentrated seawater liquid storage tank (13).

When the present invention works:

The linear Fresnel concentrator is centered on the solar chimney and distributed obliquely in the circumferential direction. After primary filtration, the seawater is pumped to the seawater preheater, where it is exchanged with the wet steam of the outer chimney and the hot air of the inner chimney. The temperature is increased by heat, and then the flow is diverted by the circumferential liquid distribution pipe and then slowly enters the blackened heat-absorbing surface to form a seawater liquid film. Solar energy is concentrated in a linear Fresnel manner to heat the blackened heat absorbing surface, which in turn heats the seawater film below it to generate steam. The blackened heat-absorbing surface is stepped, which can effectively increase the evaporation of seawater. The concentrated seawater produced by the evaporation of seawater flows into the concentrated seawater tank under the heat absorbing plate on the bottom of the heat collection shed, where heat energy is stored for use when there is no sun. After the thick seawater tank is full, it will flow out from the thick seawater output pipe. The air enters the system in two ways, and part of the air is heated by a linear Fresnel concentrator to generate buoyancy, and is quickly swept over the seawater film, causing the seawater film to evaporate rapidly and the air humidity to increase significantly. The moist air enters the interlayer of the inner and outer chimneys under the action of the buoyancy force, and then flows to the seawater preheater, where the flow space of the moist air suddenly increases, coupled with the action of the seawater preheater, condenses into fresh water and drips into the water receiving tank below. Store in fresh water tanks. The other part of the air passes through the air interlayer formed between the heat-absorbing plate on the bottom of the heat-collecting shed and the heat-absorbing plate on the bottom of the heat-collecting shed. The external environment forms a density difference, resulting in a pressure difference, which generates a strong updraft to drive the wind turbine placed in the center of the bottom of the inner chimney, thereby driving the generator to generate electricity, and then flows to the outer chimney. At this time, the air is still rising hot air, which can eject the humid air passing through the seawater preheater, and continue to rise after the two channels of the chimney are finally mixed together and enter the outer chimney. Secondary condensation forms fresh water that drips along the wall of the outer chimney. The condenser is inclined and symmetrically arranged, so that fresh water can be collected to the wall of the outer chimney, and the part of the condenser protrudes out of the chimney to form a natural circulation inside the condenser, and the water with high temperature will circulate to the part of the condenser outside the chimney from the outside The environment is air-cooled, and the low-temperature water circulates to the bottom of the condenser to cool the rising wet steam. At the same time, the condenser can be cooled by using the lower ambient temperature at night due to its high location.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects: it has a circumferentially arranged inclined heat collection shed, which can enhance the safety of the chimney while increasing the amount of absorbed solar radiation; it has two chimneys inside and outside, and the air It enters the system in two ways, and the optimization of air distribution can improve the efficiency of seawater desalination; in the equatorial region, the linear Fresnel concentrator is centered on the solar chimney, and is evenly distributed in the circumferential direction, which can increase the concentration of the collector. heat area, and improve its heat collection efficiency; using a condenser can effectively improve the condensation efficiency of water vapor; the condenser is arranged in a tilted symmetry, so that fresh water can be collected to the wall of the outer chimney, and part of it protruding from the outside of the chimney can make the inside of the condenser form a natural cycle, so that no additional energy input is required.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic diagram of the present invention embedded double-chimney solar seawater desalination system.

Fig. 2 is a structural diagram of the linear Fresnel type concentrator of the present invention.

Fig. 3 is a sectional view of the condenser in the outer chimney.

In the picture:

1. Inner chimney, 2. Outer chimney, 3. Linear Fresnel concentrator, 4. Wind turbine, 5. Transparent heat collection shed, 6. Seawater preheater, 7. Condenser, 8. Seawater Input pipe, 9. Seawater circumferential liquid distribution pipe, 10. Water tank, 11. Fresh water tank, 12. Heat absorbing plate on the bottom of the heat collection shed, 13. Concentrated seawater heat storage tank, 14. Vent, 15. Fresh water output Pipe, 16, dense seawater output pipe, 17, support group, 18, fresh water connecting pipe, 19, Fresnel lens, 20, blackened heat-absorbing surface.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings. As shown in Figure 1, a built-in double-chimney solar desalination system includes an inner chimney 1, an outer chimney 2, a linear Fresnel concentrator 3, a transparent heat collection shed 5, and a seawater preheater 6 , condenser 7, seawater input pipe 8, water receiving tank 10, fresh water tank 11, heat absorbing plate 12 at the bottom of the heat collection shed, concentrated seawater heat storage tank 13, support group 17, fresh water connecting pipe 18; the inner chimney 1 is embedded in Inside the outer chimney 2, a seawater preheater 6 is installed under the outlet of the inner chimney 1, and a condenser 7 is built in the outer chimney 2; the bottom of the inner chimney 1 is connected to a transparent heat collection shed 5, and a water tank 10 is set at the connection, and the water tank 10 passes through The fresh water connecting pipe 18 is connected to the fresh water tank 11. The bottom of the transparent heat collecting shed 5 is supported by multiple sets of support groups 17. The support group 17 is located above the heat absorbing plate 12 on the bottom surface of the heat collecting shed which is arranged in a ring. The Fresnel type concentrating heat collector 3, the concentrated seawater heat storage tank 13 is arranged under the heat absorbing plate 12 on the bottom surface of the heat collecting shed, and the horizontal seawater input pipe 8 is arranged under the concentrated seawater heat storage tank 13.

A wind turbine 4 is arranged at the bottom of the above-mentioned inner chimney 1 .

The above-mentioned linear Fresnel type concentrating heat collector 3 is composed of a Fresnel lens 19 and a blackened heat absorbing surface 20 , and the Fresnel lens 19 is wider than the blackened heat absorbing surface 20 .

The above-mentioned blackened heat absorbing surface 20 adopts black paint and is stepped.

The seawater circumferential liquid separator 9 is arranged inside the outer chimney 2 , and the seawater circumferential liquid separator 9 is connected to the blackened heat-absorbing surface 20 .

The fresh water tank 11 is horizontally provided with a fresh water output pipe 15, and the concentrated seawater heat storage tank 13 is horizontally provided with a concentrated seawater output pipe 16.

The above-mentioned condenser 7 is higher than the outlet of the inner chimney 1, and is arranged obliquely and symmetrically.

The above-mentioned transparent heat collecting shed 5 is provided with vents 14 .

A method for desalination of seawater with built-in double-chimney solar energy. After primary filtration, the seawater is pumped to the seawater preheater 6, where it exchanges heat with the external wet steam to increase the temperature, and then the seawater is distributed by the circumferential liquid pipe 9. Slowly flow into the blackened heat-absorbing surface 20, forming a seawater liquid film on the heat-absorbing surface, so that the Fresnel lens 19 condenses and heats the blackened heat-absorbing surface 20, and then evaporates the seawater film above the heat-absorbing surface, resulting in Water vapor and thick seawater then flow into the thick seawater tank 13, where heat energy is accumulated for use when there is no sun. After the thick seawater tank water storage is full, then flow out by the thick seawater output pipe 16. The linear Fresnel concentrator 3 is arranged circumferentially around the chimney, and can be adjusted according to its placement position and the position of the sun in order to make the concentrator more efficient. The air is divided into two paths, one path flows in from the linear Fresnel concentrating heat collector 3, and the other path enters the inner chimney 1 between the transparent heat collecting shed 5 and the heat absorbing plate 12 on the bottom surface of the heat collecting shed. In the linear Fresnel concentrating heat collector 3, the air is swept from above the seawater film, and the air humidity increases greatly when the seawater film evaporates rapidly. The moist air enters the inner and outer chimney walls under the action of the buoyancy force and the jet ejection of the inner chimney 1, and then flows to the seawater preheater 6, where the flow space of the moist air suddenly increases and the action of the seawater preheater 6 condenses into fresh water Drip into the water receiving tank 10 below and then deposit in the fresh water tank 11. Between the transparent heat-collecting shed 5 and the heat-absorbing plate 12 on the bottom of the heat-collecting shed, the air is heated when it flows through the heat-collecting shed, so that the temperature rises and the density decreases. 2. In the outer chimney, it mixes with the humid air passing through the seawater preheater 6 and enters the condenser 7, where it continues to condense part of the steam, and then discharges it into the atmosphere. Wind turbine 4 is reserved for peak regulation. The electric energy obtained by wind power generation is stored in the storage battery after frequency modulation by the inverter, and then the pump is driven to make the seawater flow into the seawater input pipe 8 . Can directly be used as electric heating seawater film or concentrated seawater storage tank 13 if there is electric energy surplus.

Claims (9)

1. A built-in double-chimney solar desalination system, characterized in that it includes an inner chimney (1), an outer chimney (2), a linear Fresnel-type concentrator (3), a transparent heat collection shed ( 5), seawater preheater (6), condenser (7), seawater input pipe (8), water tank (10), fresh water tank (11), heat-absorbing plate on the bottom of the heat collection shed (12), concentrated seawater Heat storage tank (13), support group (17), fresh water connecting pipe (18); the inner chimney (1) is embedded in the outer chimney (2), and a seawater preheater ( 6), the outer chimney (2) has a built-in condenser (7); the bottom of the inner chimney (1) is connected to a transparent heat collection shed (5), and a water receiving tank (10) is arranged at the connection, and the water receiving tank (10) Connect the fresh water tank (11) through the fresh water connecting pipe (18), the bottom of the transparent heat collecting shed (5) is supported by multiple sets of support groups (17), and the support groups (17) are located in the heat collecting Above the heat-absorbing plate (12) on the bottom of the shed, a linear Fresnel-type concentrating heat collector (3) is arranged obliquely on the upper end of the support group (17), and below the heat-absorbing plate (12) on the bottom of the heat-collecting shed A concentrated seawater heat storage tank (13) is provided, and a horizontal seawater input pipe (8) is provided below the concentrated seawater heat storage tank (13). 2. A built-in double-chimney solar seawater desalination system according to claim 1, characterized in that: a wind turbine (4) is installed at the bottom of the inner chimney (1). 3. A built-in double-chimney solar desalination system according to claim 1, characterized in that: the linear Fresnel concentrator (3) is composed of a Fresnel lens (19) and a coating The black heat absorbing surface (20), the Fresnel lens (19) is wider than the black heat absorbing surface (20). 4. The built-in double-chimney solar seawater desalination system according to claim 3, characterized in that: the blackened heat-absorbing surface (20) is made of black paint and is stepped. 5. An embedded double-chimney solar seawater desalination system according to claim 1, characterized in that: the outer chimney (2) is provided with a seawater circumferential separator (9), and the seawater circumferential The liquid separator (9) links to each other with the blackened heat-absorbing surface (20). 6. A built-in double-chimney solar seawater desalination system according to claim 1, characterized in that: the freshwater tank (11) is provided with a freshwater output pipe (15) horizontally, and the concentrated seawater heat storage tank (13 ) to set the concentrated seawater output pipe (16) horizontally. 7. A built-in double-chimney solar seawater desalination system according to claim 1, characterized in that: the condenser (7) is higher than the outlet of the inner chimney (1), and is arranged obliquely and symmetrically. 8. A built-in double-chimney solar seawater desalination system according to claim 1, characterized in that: the transparent heat collection shed (5) is provided with a vent (14). 9. A method for desalination of seawater with embedded double-chimney solar energy, characterized in that the system according to claims 1-8 is used, comprising the steps of: (1) After primary filtration, the seawater is pumped to the seawater preheater (6), where it exchanges heat with the external wet steam to increase the temperature, and then slowly flows into the coating from the seawater circumferential liquid pipe (9). On the black heat-absorbing surface (20), a seawater liquid film is formed on the heat-absorbing surface, so that the Fresnel lens (19) concentrates and heats the black heat-absorbing surface (20), and then evaporates the seawater film above the heat-absorbing surface , water vapor is generated, and the concentrated seawater flows into the concentrated seawater tank (13), where heat energy is accumulated for use when there is no sun, and the concentrated seawater tank is filled with water and flows out from the concentrated seawater output pipe (16); (2), the air is divided into two paths, one path flows in from the linear Fresnel concentrating heat collector (3), and the other path enters from between the transparent heat collecting shed (5) and the heat absorbing plate (12) on the bottom surface of the heat collecting shed In the inner chimney (1), in the linear Fresnel concentrator (3), the air is blown from above the seawater film, and the air humidity increases greatly when the seawater film evaporates rapidly, and the moist air is affected by the buoyancy force and the inner chimney (1) Under the action of jet ejection, it enters the inner and outer chimney walls, and then flows to the seawater preheater (6), where the humid air flow space suddenly increases and the action of the seawater preheater (6) condenses into fresh water dripping into the The lower water receiving tank (10) is then stored in the fresh water tank (11); between the transparent heat collecting shed (5) and the heat absorbing plate (12) on the bottom of the heat collecting shed, when the air flows through the transparent heat collecting shed (5) It is heated, so that the temperature rises and the density decreases, and enters the inner chimney (1) under the action of chimney buoyancy, and then flows to the outer chimney (2); (3) In the outer chimney (2), it is mixed with the humid air passing through the seawater preheater (6) and enters the condenser (7), where it continues to condense part of the steam and then discharges it into the atmosphere; (4) The wind turbine (4) is reserved for peak regulation; the electric energy obtained by wind power is stored in the battery after frequency modulation by the inverter, and then the pump is driven to make seawater flow into the seawater input pipe (8). If there is surplus electric energy It can be directly used as an electrically heated seawater film or a concentrated seawater liquid storage tank (13).