CN105174339A - Forward-condensing multiple-effect back-heating array type humidification and dehumidification solar-powered seawater desalination device - Google Patents

Abstract

The invention discloses a forward concentrating multi-effect heat recovery array type air humidification and dehumidification solar seawater desalination device, which comprises a concentrator, a humidifier, a condenser and an air duct. The sunlight incident from above is concentrated by the concentrator and penetrates the glass cover plate, and reaches the surface of the humidifier to be converted into heat energy. The seawater is sprayed onto the humidifier, absorbing the heat of the sun, and exchanging heat and moisture with the air to form saturated humid air. Driven by the fan, the high-temperature humid air enters the condensation chamber to exchange heat with cold seawater to form fresh water. After the seawater leaves the condenser, part of the seawater is sprayed onto the humidifier, and the rest is discharged from the system. The unevaporated brine drips into the brine pan and is recycled, and the excess brine is discharged from the device through the bottom of the pan. The device can be arrayed into a multi-effect system, and each effect has the same structure. The high-temperature humid air and the brine in the brine pan are sent to the other effect to heat the brine in the condenser and cool the humid air respectively, and recover the latent heat released when the steam condenses, realizing The purpose of efficient desalination of seawater.

Description

Forward concentrating multi-effect heat recovery array type humidification and dehumidification solar seawater desalination device

technical field

The invention relates to a device for directly heating seawater by concentrating solar energy to evaporate it, and extracting fresh water through an air humidification and dehumidification process, belonging to the technical fields of solar heat utilization, seawater desalination and water treatment. Specifically, it relates to a forward concentrating multi-effect heat recovery array type humidification and dehumidification solar seawater desalination device.

Background technique

At present, the biggest problem of solar desalination is high cost and small scale. In terms of cost, the current water production price of a large-scale reverse osmosis desalination system is about 5-8 yuan/ton; a large-scale low-temperature multi-effect seawater desalination system is generally combined with a power plant, and the cost is about 8-10 yuan. As for the solar desalination system, the current price of water production is more than 20 yuan/ton. This is based on the system life of 20 years and an average water production of 12 liters/day per square meter of collectors. The actual price may be higher than this. In terms of scale, the largest solar desalination system in the world currently only has tens of tons of water per day, which is far behind the reverse osmosis system, and cannot match the water production of the low-temperature multi-effect system. These bottlenecks have plagued the prospects for solar desalination technology.

Aiming at the above problems, a technical scheme of direct heating of seawater desalination by forward concentrating light is proposed. Its feature is to directly transport light into seawater, and directly cause seawater to evaporate, and then reuse the latent heat of steam condensation, so that the concentrator, receiver, heat storage, pipeline and desalinator are integrated into one. Turn it into a concentrated system, thereby reducing the resistance of energy transfer, and using non-metallic materials as much as possible to achieve the goals of corrosion resistance and low cost.

Contents of the invention

In view of this, in order to improve the performance of the existing solar seawater desalination device, increase its thermal energy utilization rate, and realize the coupling of solar energy concentrating heat collection technology and new humidification and dehumidification traditional seawater desalination technology, the present invention provides a forward concentrating multi- The seawater desalination device with efficient heat recovery array humidification and dehumidification adopts concentrated light direct heating multi-effect humidification and dehumidification system to realize multi-effect recovery of humidification and dehumidification system and improve the heat utilization efficiency of the system. The concentrator uses a designed Fresnel lens for concentrating light, and can also use a trough CPC concentrator and other forward concentrators. Here, the light receiver is the evaporator of the desalination system, which condenses multiple systems together, greatly reducing the heat transfer resistance of the system and reducing the components of the system.

A forward concentrating multi-effect heat recovery array type humidification and dehumidification solar seawater desalination device, the seawater desalination device includes a concentrator, a transparent glass cover plate, a humidifier, a condenser, a salt water pan, a hot and cold air duct, a circulating water pump, Control valve. The inside of the humidifier contains a shower, black porous material and a salt water pan. The humidifier and condenser are distributed up and down to form an independent unit.

Working principle: The sun rays incident vertically along the concentrator pass through the concentrator and the secondary concentrator and converge to the glass cover plate, and then pass through the cover plate and enter the humidifier made of black porous material. Spray on the humidifier through the sprinkler, and exchange heat and moisture with the air to form moist saturated steam. Driven by the fan in the air duct, the humid air enters the next-stage condenser to condense into fresh water. The concentrated seawater at the bottom of the brine pan is pumped to the next-stage condenser through the circulating water pump, and the concentrated seawater absorbs the latent heat of vaporization in the condenser, and then returns to the humidification chamber of the current stage for spraying. The unit structure of each level is exactly the same, and the air in the enclosed space is continuously circulated under the action of the fan, and is continuously humidified and then dehumidified between each effect. The energy recovery stage does not use concentrated light for heating, but only recovers the heat energy in the brine pan and the first-stage condenser. It is a single-stage heat recovery humidification and dehumidification system.

The secondary concentrator is to re-converge individual scattered light into the scope of the transparent glass cover, and the glass cover is made of ultra-clear glass to enhance the permeability. The surface of the porous material has a hydrophilic film, which is evenly distributed in the humidification chamber as a humidifier.

Beneficial effect:

(1) Fresnel lens, compound paraboloid and other similar concentrators are used for concentrating, and the sunlight directly shines on the heating coil on the outer wall and the black porous material in the humidification chamber. The seawater directly absorbs sunlight, uses strong light to directly evaporate seawater, omits a heat exchanger, reduces heat transfer links, and improves heat collection efficiency.

(2) The black porous material fills the humidifier, which can increase the optical path of sunlight in the evaporator, strengthen the absorption efficiency of seawater to solar heat energy, and improve the reliability of the device.

(3) By adopting a plastic condenser, the entire device can be made of non-metallic materials, thereby improving the corrosion resistance of the entire system; reducing the cost and weight of the device, which is conducive to popularization and application.

(4) The use of multi-effect spraying system and hydrophilic black porous ceramics improves the heat and mass transfer between feed seawater and air, as well as the moisture content of humid air, and increases the contact area between seawater and air. The thermal method reduces the temperature difference between the feed seawater and the heating temperature and saves heat energy.

The invention improves the traditional dehumidification and humidification type solar seawater desalination system, and realizes multi-effect heating. In terms of heat utilization, the concentrated seawater at the bottom of the brine pan is heated by a condenser and then sprayed to produce water and humid air, making full use of the humid air. The latent heat of condensation of the air is combined with multi-stage humidification and dehumidification, and each effect makes full use of the heat energy obtained. In such a device, the heat energy utilization of each effect is relatively balanced.

Description of drawings

Fig. 1 is the schematic diagram of the seawater desalination machine using single-stage Fresnel concentrating humidification and dehumidification in the present invention;

Fig. 2 is the schematic diagram of the present invention adopting Fresnel light concentrating five-stage seawater desalination machine;

Fig. 3 is the formation principle diagram of the compound paraboloid of concentrator of the present invention;

Fig. 4 is the schematic diagram of the optical path operation of the compound parabolic seawater desalination machine of the present invention;

Fig. 5 is the three-dimensional structure diagram of the present invention adopting compound parabolic two-row five-stage array trough-type seawater desalination machine;

Fig. 6 is a schematic diagram of a trough-type seawater desalination machine adopting multiple compound paraboloid arrays in the present invention.

Among them, 1—sun incident light; 2—forward concentrator; 3—secondary concentrator; 4—glass cover; 5—sprinkler; 6—water replenisher; 7—humidifier; 8—control valve ;9—salt water tray; 10—hot air passage; 11—circulating water pump; 12—concentrated discharge outlet; 13—fresh water outlet; 14—seawater inlet; 15—condenser; 16—fan; 17—cold air passage; ; 19—fresh water outlet; 20—incident light on the outer edge of the paraboloid; 21—incident light on the inner edge of the paraboloid; 22—reflecting surface of the paraboloid; 23—insulation material; f1—focus of the left paraboloid;

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and examples.

As shown in Figures 1 and 2, the present invention provides a forward concentrating multi-effect heat recovery array type humidification and dehumidification solar seawater desalination device, the device mainly includes a concentrator 2, a secondary concentrator 3, and a shower 5. Humidifier 7, control valve 8, salt water pan 9, circulating water pump 11, condenser 15 and fan 16; among them, the concentrator adopts self-made Fresnel arc-shaped lens, and the secondary concentrator adopts compound parabolic reflector aluminum plate. The secondary concentrator is attached at the edge of the humidification and dehumidification unit.

As shown in Figure 2, from right to left are the heat recovery stage, the first stage, the second stage, the third stage, the fourth stage and the final stage humidification and dehumidification seawater desalination unit. The seawater desalination machine connects a plurality of humidification and dehumidification type seawater desalination units in series array, and the feed seawater enters the device through a series of horizontal arrays to participate in the desalination process, forming a multi-stage solar humidification and dehumidification type seawater desalination device. The converging light is transmitted through the glass cover plate 4 by a forward concentrator to condense and directly heat the humidifier 7 . The brine pan 9 of every level is connected by pipeline, guarantees that equal water yield is arranged like this. The brine tray 9 collects the seawater dripping from the humidifier 7, and sprays the seawater into the humidifiers 7 at all levels through the bottom circulating water pump 11 and the sprinkler 5, so as to realize the process of isothermal heating of the seawater and perform heat-humidity with the air. The wet saturated steam formed by the exchange is driven by the fans 16 in the first and last stage units, and circulates in the humidification and dehumidification units at all levels to realize the process of humidification and dehumidification; the high-temperature and high-humidity steam is fed to the condenser Seawater undergoes heat exchange and condensation to generate fresh water, and at the same time preheats the feed seawater, realizing the process of multi-stage isothermal heating and multi-effect heat recovery, and improving the heat utilization efficiency of solar energy.

The specific connection method is shown in Figure 2. The feed seawater first enters the humidification and dehumidification unit of the energy recovery stage. This unit is not within the concentrating range of the concentrator 2, and is only used to recover part of the sensible heat of the seawater in the first-stage condenser. The fan 16 in the first stage sends the high-temperature and high-humidity steam in the humidifier 7 into the condenser 15 of the second stage through the air duct, exchanges heat with the cooler seawater inside the condenser 15, and condenses to generate fresh water. The feed seawater is preheated. The condensed air enters the humidifier 7 of the third stage, and the high-temperature and high-humidity steam generated is sent to the fourth-stage dehumidification chamber for condensation, and the condensed air enters the final humidifier. The fan in the final stage, boosting the air, passes through in turn, the final stage dehumidification chamber, the fourth stage humidification chamber, the third stage dehumidification chamber, the second stage humidification chamber and the first stage dehumidification chamber, so that the air in the humidification chamber and dehumidification chamber The cavities are staggered through, forming a complete closed cycle of coming and going. Throughout the device, the concentrated brine in the previous stage of brine pan is always sent to the rear stage condenser by the circulating water pumps 11 of each stage, and then sprayed on the rear stage humidifier. Only the concentrated brine in the final level of brine pan is pumped into this level of humidifier for spraying.

As shown in accompanying drawing 3, the parabolic reflective surface formed by the parabolic reflective surface inside the left and right concentrators is a compound parabolic reflective surface. The composite parabolic reflector is a plane parabola that is translated to the right along the horizontal axis by a distance of twice the focal length of the parabola and intersects with the right half of the original parabola. Cut off the remaining cone-shaped parabola graph with a straight line, extend the two lower end points of the truncated graph vertically into a line, reach the design length and tangent to a semicircle respectively, connect the two tangent points horizontally, and the resulting graph can be obtained A trough compound paraboloid.

As shown in accompanying drawing 4 and 5, the paraboloid outer edge incident ray 21 is the boundary ray incident to the paraboloid reflection surface, and the paraboloid inner edge incident ray 22 is the boundary ray incident to the paraboloid reflection surface inner edge, and the paraboloid outer edge incident ray 21 and The incident rays between the incident rays 22 in the paraboloid along the symmetry axis can all irradiate on the paraboloid reflective surface 23 and be reflected on the glass cover 4 .

Two sets of five-stage array humidification and dehumidification devices are placed side by side under the compound paraboloid. The incident light reflected by the parabolic reflective surface 23 enters the humidifier 7 through the glass cover plate 4, and continuously heats the humidifier 7. The periphery and the bottom of the device are covered by thermal insulation material 24 to prevent the device from radiating heat to the outside. The light receiver part under the compound paraboloid is the evaporator of the five-stage desalination unit, which condenses multiple units together, greatly reducing the heat transfer resistance and system components of the system. Located outside the compound parabolic concentrator is a humidification and dehumidification unit for energy recovery. There are fresh water outlets 13 at the bottom of the five-stage desalination device under the compound parabola and the external humidification and dehumidification unit for energy recovery. Both sets of energy recovery units have seawater inlets 14 on their front sides, connected to internal condensers 15 .

As shown in Figure 6, several trough-type compound parabolic concentrating direct heat desalination devices are connected in series and connected with cold and hot air ducts through water supply and drainage pipes. The incident light directly heats the humidifiers in each device respectively, and the seawater enters from the energy recovery stage on the right. The brine pan 9 in each trough device is connected by a pipeline passing through the outer wall, so as to ensure that every effect has an equal amount of water. The high-temperature saturated humid air circulates in the humidifier and dehumidifier of each device, and the fresh water is condensed through the condenser, which is output to the system through the fresh water outlet 13 at the bottom of each device, and further collected. The low-temperature air enters the humidifier 7 to regain high-temperature saturated humid air, and the cycle goes on and on.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. Forward concentrating multi-effect heat recovery array type air humidification and dehumidification solar desalination device, characterized in that the device includes a forward concentrator (2), a transparent glass cover (4), a shower (5 ), humidifier (7), salt water tray (9), hot air duct (10), condenser (15) and cold air duct (17); The solar concentrator of light, the focal spot and the sun are respectively located on both sides of the concentrator, and the concentrator is placed on the upper part of the desalination device. The secondary light concentrator (3) is separately arranged on both sides of the transparent glass cover plate, and is used for converging part of the scattered light, which is the secondary converging of the incident light. The device is divided into upper and lower parts with the brine plate as the boundary, the upper part is an evaporation chamber, and the lower part is a condensation chamber, and the evaporation chamber and the condensation chamber are connected through hot air channels (10) and cold air channels (17) on both sides. The shower (5), the small shower (6) and the humidifier (7) are placed in the evaporation chamber, the condenser is placed in the condensation chamber, and the fan (16) is placed in the cold air duct (17). The forward concentrator (2) gathers sunlight (1) to the transparent window cover plate (4) and enters the evaporation chamber of the device through (4) and finally reaches the upper surface of the humidifier (7), realizing direct heating of seawater; from The seawater sprayed by the sprinkler (5) is directly heated and evaporated by light on the upper surface of the humidifier (7), and the generated steam exchanges heat and moisture with the air to form moist saturated air, which enters the condensation chamber through the hot air duct (10) , where it is cooled and condensed into fresh water by the condenser, and sent to the user through the fresh water outlet (13). The salt water tray (9) is placed in the lower part of the humidifier (7), and the salt water dripping from (7) is collected, and the salt water is sent to the sprinkler (5) for spraying again through the circulating water pump (11). 2. The forward concentrating multi-effect heat recovery array type air humidification and dehumidification solar seawater desalination device as claimed in claim 1, characterized in that its independent devices can be arrayed to form a multi-effect system, and each effect humidification and dehumidification unit has the same structure. Except for the last effect which does not accept sunlight as a heat recovery stage, all other effects accept sunlight. At the same time, except for the last effect as an independent desalination unit, the other effects are connected to each other through hot air channels and cold air channels. Seawater enters from the heat recovery stage, passes through the condenser, and then enters the condenser in the previous effect to cool the humid air in the last effect, and then part of it is used as a device to supplement seawater, and enters the first effect through the small nozzle (6) The other part returns to the heat recovery stage and is sprayed by the sprayer (5). In addition to the heat recovery stage, the hot and humid air generated in the latter stage is driven by the fan into the condensation chamber of the previous stage to exchange heat with the condenser. After the humid air is cooled, it is sent to the evaporation chamber of the previous stage for increasing Warm humidification is then sent to the previous stage of condensation chamber to be cooled until the most advanced stage. On the contrary, the high-temperature hot and humid air generated by the most preceding stage will be sent to the next-stage condensing chamber for cooling, and the cooled humid air will be sent to the next stage to increase the temperature and humidify, and so on until the last stage, forming a cycle process. 3. The forward concentrating multi-effect heat recovery array type air humidification and dehumidification solar seawater desalination device as claimed in claim 2, characterized in that all the brine in the brine pan is pumped to the previous condensation chamber by the circulating water pump (11) The hot and humid air used to cool the previous effect in the cooler in the cooler is heated and then returned to the spraying stage to form a cycle until the first stage, and the salt water in the first stage is directly pumped to the spraying stage of the present stage Spray in the device to form a closed cycle. The brine pan (9) of each effect of described is connected by pipeline, guarantees that every effect has the brine of equivalent like this.