Air dehumidification cooling and thermosiphon water recovery system and method, cooling tower and power plant

Abstract

This invention discloses an air dehumidification and cooling system and method with thermosiphon water recovery, a cooling tower, and a power plant. The system includes a tower body, a dehumidifier, a dehumidifying liquid regenerator, and a waste heat flue gas recovery unit. The dehumidifier pre-treats the high-humidity air entering the tower to enhance its cooling potential. The dry air comes into counter-current contact with circulating water inside the tower to achieve efficient evaporative cooling. When the generated humid and hot air flows through the thermosiphon array, the water vapor in it is condensed and recovered to a water collection tank. The dehumidified dilute dehumidifying liquid is sent to the regenerator, where it is regenerated by heating with waste heat flue gas from the power plant and then recycled. Through the closed-loop collaborative design of "air dehumidification pre-treatment - efficient evaporative cooling of circulating water - condensation and recovery of humid air moisture by thermosiphon - waste heat utilization to regenerate dehumidifying liquid", the system solves the dual problems of low efficiency and high water consumption of cooling towers in humid and hot environments, simultaneously improving cooling efficiency and water resource recovery rate, and achieving synergistic effects of energy saving and water saving.

Description

Technical Field

[0001] This invention relates to cooling tower equipment in the field of power generation, and more particularly to an air dehumidification and cooling and thermosiphon water recovery system and method, a cooling tower and a power plant. Background Technology

[0002] Cooling towers are key equipment used for cooling circulating water in power plants. Their core function is to effectively cool the circulating water by removing sensible and latent heat through contact between water and air, utilizing airflow and evaporative cooling. A typical mechanical draft cooling tower mainly consists of ventilation equipment, a spray water system, water-spraying packing, and a collection tank. During operation, high-temperature circulating water is evenly sprayed onto the water-spraying packing layer by the spray system. The packing disperses the water flow into a water film or fine droplets, significantly expanding the contact interface between water and air and prolonging the contact time. Simultaneously, the fan forces in ambient air, causing it to come into counter-current contact with the water flow within the packing area, completing heat and moisture exchange. After absorbing heat and moisture, the air's temperature and humidity increase, and it is eventually discharged from the top of the tower, while the cooled water falls into the collection tank and returns to the system for reuse.

[0003] In hot and humid regions (such as southern my country in summer), the relative humidity of the ambient air is often high, approaching or reaching saturation. At this time, the air's ability to hold additional water vapor decreases significantly, leading to an increase in its wet-bulb temperature and a reduction in the temperature difference between it and the cooling water, thus severely weakening the driving force of evaporative cooling. Traditional cooling towers generally face the dilemma of reduced cooling efficiency and difficulty in achieving design-required outlet water temperatures under such climatic conditions. Simultaneously, in high-humidity environments, to maintain the cooling load and compensate for losses from evaporation and dripping, the system needs to continuously replenish large amounts of water, which not only exacerbates water consumption but also increases operating costs, resulting in a double waste of energy and water resources.

[0004] To address the impact of high temperature and humidity on cooling tower performance, existing technologies typically employ measures such as enhancing gas-liquid contact or introducing auxiliary precooling. For example, improving the packing structure to increase the heat exchange area and enhance the uniformity of water distribution. However, these methods primarily focus on localized enhancement of the cooling process itself, failing to fundamentally address the key factor limiting cooling potential: inlet air humidity saturation. Therefore, performance improvements under humid and hot conditions are limited, and water conservation requirements are often not met, resulting in inefficient water recovery and a still relatively high overall system water consumption.

[0005] In summary, existing cooling tower technologies generally suffer from a difficulty in simultaneously achieving both cooling efficiency and water conservation when dealing with high-temperature and high-humidity environments, and existing improvement solutions often focus on optimizing a single aspect. Therefore, developing a cooling tower system that can adapt to high-temperature and high-humidity climates and combines high-efficiency cooling with water resource recovery functions to overcome the performance bottlenecks of traditional cooling towers and achieve synergistic effects of energy and water conservation is of great significance for solving the energy efficiency bottlenecks and water waste problems in industrial cooling in hot and humid regions. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide an air dehumidification cooling and thermosiphon water recovery system and method, a cooling tower and a power plant. Through a closed-loop synergistic design of "air dehumidification pretreatment - high-efficiency evaporative cooling of circulating water - condensation and recovery of humid air moisture through thermosiphon tube - waste heat utilization to regenerate dehumidifying liquid", the invention solves the problems of low cooling efficiency and high water consumption of traditional cooling towers under high temperature and high humidity environments, and makes full use of the abundant waste heat resources of the power plant to achieve simultaneous improvement in cooling efficiency and water recovery rate.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] An air dehumidification, cooling, and thermosiphon water recovery system for use in cooling towers of power plants, comprising:

[0009] The tower body has an axial flow fan at the top to provide forced ventilation power; the tower body is arranged from top to bottom as follows: a thermosiphon array, a water collector, a circulating water spray assembly, a wind baffle assembly, a water spraying packing and a water collection tank.

[0010] A thermosiphon array is provided, with the thermosiphon tubes arranged at an angle of 20°-45°, 0.5 m to 1.0 m above the water collector, in a single row symmetrically arranged on both sides. The array consists of 1000 thermosiphon tubes, fixed inside the cooling tower by supports. The inner and outer diameters of each tube are 18.5 mm and 20 mm, respectively. The evaporation section, insulation section, and condensation section of the thermosiphon tubes are 6.4 m, 2.2 m, and 6.4 m long, respectively, with a tube spacing of 40 mm. Distilled water is used as the medium inside the thermosiphon tubes.

[0011] A water collector, which employs a high-efficiency baffle structure to reduce droplet loss;

[0012] A water collection tank is located at the bottom of the tower body to collect the circulating water after cooling, and a drain outlet is provided at the bottom;

[0013] Furthermore, the tower body is provided with a circulating water spraying assembly, which includes a water supply pipe, nozzles and a filter plate. The two ends of the water supply pipe are respectively connected to the condenser circulating water outlet and a number of nozzles. The filter plate is placed on the top of the water collection tank and installed on the tower body.

[0014] Furthermore, the tower body is also provided with water-spraying packing, which has multiple parallelogram protrusions to form discontinuous turbulence channels.

[0015] Furthermore, the tower body is also provided with a wind baffle assembly, which includes a driving component installed on the tower body and is mainly composed of a servo motor.

[0016] Furthermore, the wind deflector assembly further includes:

[0017] A rotating shaft is arranged radially along the tower body and connected to the driving component via a bearing.

[0018] A wind deflector, wherein the wind deflector is an arc-shaped plate structure, and the wind deflector is connected to the rotating shaft by bolts.

[0019] Furthermore, in this invention, the dehumidifier is located at the air inlet of the tower body, and the dehumidifier uses a calcium chloride salt solution with a mass fraction of 30% to 45% as the dehumidification medium.

[0020] Furthermore, the dehumidifier includes a dehumidifying liquid inlet, and the dehumidifying liquid inlet and the regenerating liquid outlet are connected via...

[0021] Pipe connection;

[0022] Furthermore, the dehumidifier further includes:

[0023] The air duct has a gradually expanding structure along the airflow direction, and the ratio of the inlet cross-sectional area to the outlet cross-sectional area is 1:1.2 to 1:1.5.

[0024] The dehumidifying liquid nozzles are arranged in layers along the axial direction of the air duct, with 4-8 nozzles in each layer, evenly distributed in a ring, and the atomized particle size of the nozzles is 50-100 µm.

[0025] A dehumidifying liquid collection tank is used to collect calcium chloride salt solutions whose concentration has decreased due to the absorption of water vapor from the air.

[0026] The dehumidifier outlet is connected to the dehumidifier collection tank, and the calcium chloride salt solution is transported to the regeneration liquid inlet through a pipeline.

[0027] Furthermore, the dehumidifier uses waste heat flue gas or low-pressure extracted steam from a power plant as a heat source and is equipped with a regenerated liquid inlet, a waste heat flue gas inlet, a waste heat flue gas outlet, a regenerated liquid outlet, a regenerated liquid nozzle, and a regenerated liquid collection tank. The regenerated liquid inlet is connected to the dehumidifier's dehumidifier outlet via a pipeline, and the regenerated liquid outlet is connected to the dehumidifier's dehumidifier inlet via a high-pressure pump, forming a closed-loop circulation.

[0028] Furthermore, in this invention, one end of the waste heat flue gas recovery device is connected to the power plant turbine, and the other end is connected to the waste heat flue gas inlet of the dehumidifier regenerator, for recovering waste heat from the flue gas to heat the dehumidifier. The temperature of the power plant flue gas collected by the waste heat flue gas recovery device is 120-200 ℃.

[0029] The present invention also provides a method for air dehumidification cooling and thermosiphon water recovery using the air dehumidification cooling and thermosiphon water recovery system described above, comprising:

[0030] Air dehumidification pretreatment: Ambient air enters the dehumidifier through the air duct. The dehumidifier uses a calcium chloride salt solution with a mass fraction of 30% to 45% as the dehumidification medium. The solution is delivered to the dehumidification liquid nozzle through the dehumidification liquid inlet. The dehumidification liquid nozzle is evenly arranged along the direction of the air duct so that the dehumidification liquid forms a uniform liquid film or fine droplets.

[0031] In the circulating water evaporative cooling process, circulating water from the power plant condenser is transported through pipelines to the circulating water spray assembly. It is first atomized into fine water droplets of 50-200 µm by nozzles and evenly sprayed onto the water-spraying packing. The atomized water droplets flow downwards through the water-spraying packing, while the dehumidified dry air flows upwards in the opposite direction, creating a gas-liquid mixture. The cooled circulating water falls into the collection pool at the bottom of the tower and is filtered through a filter plate to remove impurities before being returned to the power plant condenser for reuse. The air, having absorbed heat and moisture, continues to flow upwards, entering the subsequent humid air moisture thermosiphon condensation and recovery process.

[0032] The humid air is condensed and recovered by a thermosiphon. The high-temperature and high-humidity air generated during the evaporation and cooling process of the circulating water first passes through a water collector to initially separate the entrained water droplets, and then flows through a thermosiphon array located 0.5 m to 1.0 m above the water collector. The thermosiphon array is arranged at an angle, with its evaporation section completely immersed in the humid and hot airflow above the water collector inside the tower. The condensation section of the thermosiphon extends to the outside of the tower body, and the insulation section of the thermosiphon is located at the tower wall and fixed to the wall surface. The tubes are filled with distilled aqueous solution as the heat transfer medium. When the humid air flows through the evaporation section of the thermosiphon, it comes into contact with the cool tube wall, and the water vapor in the air quickly condenses into liquid water on the tube wall and drips into the water collection pool under the action of gravity.

[0033] Waste heat recovery is used to regenerate the dehumidifying fluid. After the calcium chloride solution absorbs moisture in the dehumidifier, its concentration decreases and it falls into the dehumidifying fluid collection tank. It is then transported from the dehumidifying fluid outlet to the regeneration fluid inlet of the dehumidifying fluid regenerator through a pipeline. There, it is atomized into fine water droplets by the regeneration fluid nozzles and sprayed evenly. This allows the low-concentration calcium chloride solution to fully contact the waste heat flue gas or low-pressure extraction steam collected from the power plant turbine by the waste heat flue gas recovery unit. At this temperature, the water in the dilute solution evaporates rapidly and is discharged from the waste heat flue gas outlet with the flue gas. The mass fraction of the calcium chloride solution gradually recovers to a high hygroscopic state of 30% to 45%. The regenerated calcium chloride solution is collected in the regeneration fluid collection tank and discharged through the regeneration fluid outlet. Then, driven by a high-pressure pump, it is transported to the dehumidifying fluid inlet of the dehumidifier. After being sprayed by the dehumidifying fluid nozzles, it participates in the air dehumidification process again, realizing the closed-loop regeneration and recycling of the dehumidifying fluid.

[0034] The present invention also provides a cooling tower, including the air dehumidification cooling and thermosiphon water recovery system described above.

[0035] The present invention also provides a power plant including the cooling tower described above.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1) By pre-treating the air entering the tower through dehumidification, the humidity content of the air is significantly reduced, which fundamentally solves the problem of low efficiency of cooling towers in high humidity environments and ensures that the outlet temperature of circulating water can still meet the design requirements in high temperature and high humidity environments.

[0038] 2) By recovering water vapor from humid air through a thermosiphon array, the traditional cooling tower mode of "directly discharging hot and humid air" is improved, which can effectively reduce evaporation loss, improve the system water saving rate, significantly reduce the amount of fresh water replenishment for power plants, and achieve efficient recycling of water resources.

[0039] 3) The water spraying packing adopts a discontinuous disturbance-type flow channel structure, which enhances heat exchange while effectively reducing the risk of blockage and improving system stability.

[0040] 4) Make full use of the low-grade waste heat of the power plant as a heat source for the regeneration of dehumidifying liquid, reduce system operating costs, and achieve efficient cascade utilization of energy.

[0041] The following detailed description, in conjunction with the accompanying drawings, illustrates the present invention's air dehumidification, cooling, and thermosiphon water recovery system and method, as well as the cooling tower and power plant: Attached Figure Description

[0042] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0043] Figure 1This is a schematic diagram of the overall structure of the power plant dehumidification-water-saving cooling tower provided by the present invention.

[0044] Figure 2 This is a schematic diagram of the dehumidification-regeneration system for a power plant cooling tower provided by the present invention.

[0045] Figures 1-2 In the accompanying drawings, the reference numerals include:

[0046] 1. Tower body;

[0047] 2. Fan;

[0048] 3. Thermosiphon array; 301. Thermosiphon condensation section; 302. Thermosiphon insulation section; 303. Thermosiphon evaporation section;

[0049] 4. Water collector;

[0050] 5. Circulating water spray assembly; 501. Water supply pipe; 502. Spray nozzle; 503. Filter plate;

[0051] 6. Wind deflector assembly; 601. Drive component; 602. Rotating shaft; 603. Wind deflector;

[0052] 7. Water spraying filler; 701. Parallelogram protrusion; 702. Turbulence channel;

[0053] 8. Catchment pool;

[0054] 9. Dehumidifier; 901. Dehumidifier fluid inlet; 902. Dehumidifier fluid nozzle; 903. Air duct; 904. Dehumidifier fluid collection tank; 905. Dehumidifier fluid outlet;

[0055] 10. Dehumidifier regenerator; 1001. Regenerated liquid inlet; 1002. Waste heat flue gas inlet; 1003. Waste heat flue gas outlet; 1004. Regenerated liquid outlet; 1005. Regenerated liquid nozzle; 1006. Regenerated liquid collection tank;

[0056] 11. Waste heat flue gas recovery unit. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] The core of this invention is to provide an air dehumidification and cooling and thermosiphon water recovery system and method, a cooling tower and a power plant, which reduces the humidity of the air at the inlet of the cooling tower and reduces the evaporation loss of the cooling tower, thereby improving the cooling capacity and water-saving capacity of the cooling tower.

[0059] Please refer to Figure 1 and Figure 2 A high-efficiency cooling and thermosiphon water recovery system for air dehumidification in power plant cooling towers in hot and humid regions includes a tower body 1, a dehumidifier 9, a dehumidifying liquid regenerator 10, and a waste heat flue gas recovery unit 11. A fan 2 is installed at the top of the tower body 1, and the interior is arranged from top to bottom as follows: a thermosiphon tube array 3, a water collector 4, a circulating water spray assembly 5, a wind baffle assembly 6, a water spraying packing 7, and a water collection pool 8. The dehumidifier 9 is located at the air inlet of the tower body 1 and is connected to the air inlet channel of the tower body 1. The dehumidifying liquid regenerator 10 forms a closed-loop circulation circuit with the dehumidifier 9 through a pipeline for regenerating the dehumidifying liquid. The waste heat flue gas recovery unit 11 is connected to the dehumidifying liquid regenerator 10.

[0060] In this embodiment of the invention, preferably, the tower body 1 is made of steel or concrete, which has good corrosion resistance and structural strength. A fan 2 is installed at the top of the tower body 1 for forced airflow to enhance air circulation inside the tower. The air inlet is located at the lower part of the tower body 1, and the air outlet is located at the top of the tower.

[0061] In this embodiment of the invention, preferably, the thermosiphon array 3 is inclined at a distance of 0.5 m to 1.0 m above the water collector, with an inclination angle of 20°-45°, and is arranged symmetrically on both sides in a single row. The thermosiphon array 3 consists of 1000 thermosiphon tubes, which are fixed inside the cooling tower by a support. The inner and outer diameters of a single tube are 18.5 mm and 20 mm, respectively. The lengths of the thermosiphon evaporation section 303, the thermosiphon insulation section 302, and the thermosiphon condensation section 301 are set to 6.4 m, 2.2 m, and 6.4 m, respectively, with a tube spacing of 40 mm. Distilled water is used as the medium inside the thermosiphon tubes to achieve efficient recovery of water vapor from the air.

[0062] In this embodiment of the invention, preferably, the water collector 4 is a PVC baffle water collector with a baffle angle of 45º and a plate spacing of 20 mm, so as to reduce the loss of cooling tower dripping.

[0063] In this embodiment of the invention, preferably, the water-spraying packing 7 is a discontinuous disturbance-type structure made of modified polyvinyl chloride (PVC). The acute angle of the parallelogram protrusions 701 on the surface is 30°-45°, the height is 8-15 mm, the distance between adjacent protrusions is 20-30 mm, and the protrusions form a turbulence channel 702 to increase the heat exchange area of ​​the packing, prolong the contact time between the liquid film and the air, and promote the continuous redistribution of water during the falling process, causing droplet splashing and further tearing of the liquid film, thereby achieving the purpose of enhancing heat exchange efficiency and reducing the risk of packing blockage.

[0064] In this embodiment of the invention, preferably, the tower body 1 is provided with a circulating water spraying assembly 5, which includes a plurality of nozzles 502 connected to a water supply pipe 501, and the nozzles 502 uniformly disperse the circulating water onto the water spraying packing 7.

[0065] In this embodiment of the invention, preferably, the water supply pipe 501 is a ring-shaped pipe network structure made of stainless steel, and the nozzles 502 are evenly distributed on the ring-shaped pipe network. The nozzles 502 are spiral atomizing nozzles with a spray angle of 70°-120° and the overlap rate of the spray coverage area of ​​adjacent nozzles is not less than 30%.

[0066] In this embodiment of the invention, preferably, the circulating water spraying assembly 5 further includes a filter plate 503. The filter plate 503 is placed on top of the water collection tank 8 and installed on the tower body 1. It is made of stainless steel, and the filter plate 503 is detachably connected to the inner wall of the water collection tank 8 by bolts. The filter plate 503 filters the circulating water after heat exchange, avoiding any impact on the recirculation of the circulating water in the condenser.

[0067] In this embodiment of the invention, preferably, the driving component 601 is mainly a servo motor, the rotating shaft 602 is made of stainless steel and is arranged radially along the tower body 1. It is connected to the driving component 601 through bearings, and the wind baffle 603 is an arc-shaped stainless steel plate with a thickness of 3 mm. The wind baffle 603 is connected to the rotating shaft 602 through bolts to adjust the opening of the wind baffle and control the direction and angle of the air entering the water spraying filler 7.

[0068] In this embodiment of the invention, preferably, the dehumidifier 9 uses a calcium chloride dehumidification solution with a mass fraction of 30% to 45% as the dehumidification medium. The air duct 903 has a gradually expanding structure along the airflow direction and is made of high-strength stainless steel. The ratio of the inlet cross-sectional area to the outlet cross-sectional area is 1:1.2 to 1:1.5. The dehumidification liquid nozzles 902 are arranged in layers along the axial direction of the air duct 903, using pressure atomizing nozzles. Each layer has 4-8 nozzles, evenly distributed in a ring. The atomized particle size of the nozzles is 50-100 µm to uniformly spray the calcium chloride solution and ensure sufficient contact with the high-humidity air, thereby reducing its humidity. The dehumidification liquid collection tank 904 is made of stainless steel and has a drain outlet and a level gauge at the bottom.

[0069] In this embodiment of the invention, preferably, the dehumidifier regenerator 10 adopts a vertical spray tower structure, with the main body made of 316L stainless steel, possessing good corrosion resistance and high temperature resistance. The tower body has a diameter of 2.2 m and a total height of 8.5 m, and is externally equipped with a 50 mm thick rock wool insulation layer to prevent heat loss. The regenerated liquid nozzles 1005 are atomizing nozzles, arranged in a ring along the cross-section of the tower body to ensure that the dilute solution is uniformly dispersed into fine droplets and fully contacts the waste heat flue gas. The regenerated liquid collection tank 1006 is located at the bottom and is equipped with a drain outlet and a liquid level sensor. The regenerated liquid inlet 1001 of the dehumidifier regenerator 10 is located at the top of the dehumidifier and is connected to the dehumidifier outlet 905 of the dehumidifier 9 through a stainless steel pipe. The pipe is equipped with a variable frequency delivery pump and an electromagnetic flow meter to accurately control the delivery volume of the dilute solution. The regenerated liquid outlet 1004 is located at the bottom of the regenerated liquid collection tank 1006 and is connected to the dehumidifier inlet 901 of the dehumidifier 9 through a stainless steel pipe, and a high-pressure pump is installed on the pipe. The waste heat flue gas inlet 1002 of the dehumidifier 10 is connected to the waste heat flue gas recovery unit 11, and the waste heat flue gas outlet 1003 is connected to the inlet of the power plant desulfurization and denitrification system.

[0070] In this embodiment of the invention, preferably, the waste heat flue gas recovery unit and the dehumidifying liquid regenerator 10 are arranged in series. The main body of the unit is made of stainless steel and is used to collect waste heat flue gas or low-pressure extraction steam from the power plant turbine. The temperature range is 120-200 ℃.

[0071] The present invention also provides a cooling tower, including the air dehumidification cooling and thermosiphon water recovery system described above.

[0072] The present invention also provides a power plant including the cooling tower described above.

[0073] To help those skilled in the art understand the present invention, the operation processes of air dehumidification pretreatment, efficient evaporative cooling of circulating water, condensation and recovery of humid air moisture via a thermal siphon, and waste heat utilization to regenerate dehumidifying liquid in the present invention will be further described in detail below.

[0074] Air dehumidification pretreatment process:

[0075] Driven by the fan at the top of the tower, ambient air from humid and hot regions enters the dehumidifier through the ductwork, ensuring stable airflow and sufficient contact with the dehumidifying solution. The dehumidifier uses a 30%–45% (by mass) calcium chloride (CaCl2) salt solution as the dehumidifying medium. This solution is delivered to the dehumidifying liquid nozzles through the inlet. These nozzles are evenly distributed along the ductwork, forming a uniform liquid film or fine droplets, effectively increasing the gas-liquid contact area and contact time, allowing the dehumidifying liquid to directly and fully contact the upward-flowing air. Because the partial pressure of water vapor in the ambient air is higher than the surface vapor pressure of the calcium chloride solution, moisture in the air spontaneously migrates into the salt solution. The salt solution then absorbs this moisture, thus dehumidifying the air. After dehumidification, the relative humidity of the air decreases, fundamentally breaking the limitation that the air is close to saturation and has weak moisture absorption capacity in a humid and hot environment, providing huge theoretical cooling potential for the subsequent evaporative cooling process of the air in the packing area; while the mass concentration of the calcium chloride solution that has absorbed moisture decreases, becoming a dilute solution, falling into the dehumidification liquid collection pool, and being transported to the dehumidification liquid regenerator through the dehumidification liquid outlet.

[0076] High-efficiency evaporative cooling process of circulating water:

[0077] High-temperature circulating water from the power plant condenser is piped to the circulating water spray assembly. It is first atomized into fine droplets of 50-200 µm by nozzles and then evenly sprayed onto the water-spraying packing. The atomized water droplets flow downwards through the packing, while dehumidified dry air flows upwards against the flow, creating a strong gas-liquid mixing contact. This cooling process relies not only on sensible heat exchange but also on enhanced latent heat exchange, thereby reducing the circulating water outlet temperature. The water-spraying packing employs a discontinuous turbulent flow channel structure. The parallelogram-shaped protrusions on its surface have acute angles of 30°-45°, a height of 8-15 mm, and a spacing of 20-30 mm between adjacent protrusions, forming discontinuous turbulent channels. The water-spraying packing, with its unique parallelogram-shaped protrusions, significantly increases the heat exchange area of ​​the packing, prolonging the contact time between the liquid film and air, thus ensuring more thorough heat exchange between the circulating water and air. Furthermore, it promotes continuous redistribution of the water during its descent, facilitating droplet splashing and further tearing of the liquid film, thereby enhancing heat exchange efficiency and effectively reducing the risk of packing blockage. The cooling process of the circulating water mainly relies on evaporative and contact heat dissipation. Dry air, due to its low moisture content and strong hygroscopic capacity, greatly enhances the heat exchange process between it and the water droplets, carrying away a significant amount of latent heat. The combined effect of the dry air and the unique protrusions of the water-spraying packing causes the circulating water temperature to drop rapidly. The cooled circulating water falls into the collection pool at the bottom of the tower and is filtered through a filter plate (1-2 mm filtration accuracy) to remove impurities before returning to the power plant condenser for reuse, preventing clogging of the nozzles and water-spraying packing during recirculation. The air, having absorbed heat and moisture, becomes high-temperature, high-humidity air and continues to flow upwards, entering the subsequent humid air-moisture thermosiphon condensation and recovery process.

[0078] Moisture recovery process of humid air with thermal siphon:

[0079] The high-temperature, high-humidity air generated during the efficient evaporative cooling process of circulating water first undergoes preliminary water droplet separation by a water collector, and then flows through a thermosiphon array located 0.5 m to 1.0 m above the water collector. The thermosiphon array is arranged at an angle (20°-45°), with its evaporation section completely immersed in the humid airflow above the water collector inside the tower. The condensation section extends to the outside of the tower, and the insulation section is located at and fixed to the tower wall. The tubes are filled with distilled aqueous solution as the heat transfer medium. As the humid air flows through the evaporation section of the thermosiphon, it comes into contact with the cooler tube wall, causing water vapor in the air to rapidly condense into liquid water. This water then drips into the collection pool under gravity. This process improves upon the traditional cooling tower model of "directly discharging humid air," enabling the active recovery of water resources about to be released into the atmosphere, thereby reducing evaporation losses and enhancing the water-saving performance of the cooling tower. Simultaneously, this process releases a large amount of latent heat of phase change. This latent heat, along with the sensible heat of the air, is absorbed by the working fluid inside the tube, causing the liquid working fluid inside the tube to evaporate into a gaseous state. This gaseous state then rapidly rises through the adiabatic section of the thermosiphon tube to the condensing section outside the tower. Outside the condensing section of the thermosiphon tube, ambient air flows naturally, carrying away the heat from the working fluid vapor, cooling the vapor and causing it to condense into liquid working fluid on the tube wall. Under the influence of gravity, this liquid flows back along the tube wall to the evaporation section of the thermosiphon tube, completing the closed-loop circulation of the working fluid inside the tube.

[0080] Waste heat utilization and dehumidification liquid regeneration process:

[0081] After the high-concentration calcium chloride solution absorbs moisture in the dehumidifier, its concentration decreases and it falls into the dehumidifying liquid collection tank. From the dehumidifying liquid outlet, it is piped to the regeneration liquid inlet of the dehumidifying liquid regenerator. There, it is atomized into fine droplets by the regeneration liquid nozzle and sprayed evenly, ensuring sufficient contact between the low-concentration calcium chloride solution and the waste heat flue gas or low-pressure extraction steam (120-200 ℃) collected from the power plant turbine by the waste heat recovery unit. At this temperature, the water in the dilute solution evaporates rapidly and is discharged from the waste heat flue gas outlet with the flue gas. The mass fraction of the calcium chloride solution gradually recovers to a high hygroscopic state of 30%–45%. This regeneration process is fully coupled with the low-grade waste heat of the power plant, eliminating the need for high-quality electricity or fuel. This achieves the cascade utilization of waste energy from the power plant and the efficient regeneration of the dehumidifying medium, completing a closed loop from "air dehumidification" to "solution regeneration." The regenerated high-concentration calcium chloride solution is collected in the regenerated liquid collection tank and discharged through the regenerated liquid outlet. Then, driven by a high-pressure pump, it is transported to the dehumidifying liquid inlet of the dehumidifier. After being sprayed by the dehumidifying liquid nozzle, it participates in the air dehumidification process again, realizing the closed-loop regeneration and recycling of the dehumidifying liquid.

[0082] The key point of this invention is as follows: High-temperature and high-humidity air is drawn in by fan 2 and enters dehumidifier 9 through duct 903. It comes into counter-current contact with calcium chloride solution sprayed from top to bottom, absorbing moisture and reducing its humidity. The dry air flows upward through water-spraying packing 7, coming into counter-current contact with high-temperature circulating water sprayed from top to bottom. The parallelogram-shaped protrusions 701 on the water-spraying packing 7 complete the efficient evaporative cooling process. The cooled water falls into collection tank 8 for recycling. The humid and hot air continues to rise, and when it passes through thermosiphon array 3, some water vapor in the air is condensed and recovered, falling into collection tank 8 for recycling, while the air is discharged from the top of the tower. The dehumidified dilute calcium chloride solution is sent to dehumidifier regenerator 10, where it is regenerated using waste heat from the power plant flue gas. After concentration, it returns to dehumidifier 9 for reuse.

[0083] By synergistically integrating the four stages of air dehumidification pretreatment, efficient evaporative cooling of circulating water, condensation and recovery of humid air and water through a thermal siphon, and waste heat utilization to regenerate dehumidifying liquid, this invention effectively solves the problems of low cooling tower efficiency and high water consumption in hot and humid regions, achieving a dual improvement in energy efficiency and water conservation. Under typical summer operating conditions in hot and humid regions, the outlet water temperature can be reduced by 0.8–1.5 ℃ (the higher the ambient humidity, the more significant the cooling effect; the cooling range is greater in summer than in winter); under typical winter operating conditions, the outlet water temperature can be reduced by 0.5–1.2 ℃, ensuring that the circulating water outlet temperature stably meets design requirements. Taking a 100 MW unit as an example, based on 6000 hours of operation per year, and calculating that each 1 ℃ reduction in outlet water temperature can increase unit efficiency by approximately 0.34%, approximately 2.04 million kWh of additional electricity can be generated annually. If calculated at an industrial electricity price of 0.5 yuan / kWh, the annual revenue from electricity generation would be approximately 1.02 million yuan.

[0084] This invention utilizes a thermosiphon array to condense and recover water vapor from the air, significantly reducing evaporation losses and the amount of fresh water needed for replenishment, resulting in substantial water savings. Taking a 100 MW unit's cooling tower as an example, under typical summer operating conditions, the hourly water saving is approximately 43–49 tons; under typical winter operating conditions, the hourly water saving is approximately 47–53 tons. Based on 6000 hours of annual operation, and averaging the summer and winter water savings, the annual average hourly water saving is 45–51 tons, resulting in an annual water saving of approximately 270,000–306,000 tons for the unit. If calculated at an industrial water price of 3 yuan / ton, the annual water replenishment cost savings for a 100 MW unit's cooling tower would be approximately 810,000–918,000 yuan.

[0085] The above provides a detailed description of an efficient air dehumidification and cooling system with thermosiphon moisture recovery for power plant cooling towers in hot and humid regions, as provided by this invention. The descriptions of the embodiments above are merely illustrative of the method and core concepts of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of this invention.

Claims

1. An air dehumidification, cooling, and thermosiphon water recovery system for use in cooling towers of power plants; characterized in that, include: The tower body (1) is equipped with a fan (2) at the top and has a thermosiphon array (3), a water collector (4), a circulating water spray assembly (5), a wind baffle assembly (6), a water spraying filler (7) and a water collection tank (8) arranged from top to bottom inside. A dehumidifier (9) is installed at the air inlet of the tower body (1) and is connected to the air inlet channel of the tower body (1) for dehumidifying the air entering the tower. The desiccant regenerator (10) forms a closed-loop circulation circuit with the desiccant (9) through a pipeline and is used to regenerate the dilute desiccant after moisture absorption; Waste heat flue gas recovery unit (11) is connected to the dehumidifier regenerator (10) and is used to recover waste heat flue gas or low-pressure extraction steam from the power plant to provide a heat source for dehumidifier regeneration. The dehumidifier (9) includes a dehumidifying liquid inlet (901), a dehumidifying liquid nozzle (902), an air duct (903), a dehumidifying liquid collection tank (904), and a dehumidifying liquid outlet (905); the dehumidifying liquid regenerator (10) includes a regenerating liquid inlet (1001), a waste heat flue gas inlet (1002), a waste heat flue gas outlet (1003), a regenerating liquid outlet (1004), a regenerating liquid nozzle (1005), and a regenerating liquid collection tank (1006).

2. The air dehumidification, cooling, and thermosiphon water recovery system according to claim 1, characterized in that, The dehumidifier (9) uses a calcium chloride dehumidification solution with a mass fraction of 30% to 45% as the dehumidification medium. The air duct (903) has a gradually expanding structure along the air flow direction, and the ratio of the inlet cross-sectional area to the outlet cross-sectional area is 1:1.2 to 1:1.

5. The dehumidification liquid nozzles (902) are arranged in layers along the axial direction of the air duct (903), with 4 to 8 nozzles in each layer, which are evenly distributed in a ring. The atomized particle size of the nozzles is 50 to 100 µm.

3. The air dehumidification, cooling, and thermosiphon water recovery system according to claims 1-2, characterized in that, The waste heat flue gas inlet (1002) of the dehumidifier (10) is connected to the waste heat flue gas recovery unit (11), the waste heat flue gas outlet (1003) is connected to the inlet of the power plant desulfurization and denitrification system, the external pipe of the regenerated liquid inlet (1001) is connected to the dehumidifier outlet (905), and the internal pipe is connected to the regenerated liquid nozzle (1005); the external pipe of the regenerated liquid outlet (1004) is connected to the dehumidifier inlet (901), and the internal pipe is connected to the regenerated liquid collection tank (1006), forming a closed-loop regeneration cycle of dehumidifier liquid.

4. The air dehumidification, cooling, and thermosiphon water recovery system according to claim 3, characterized in that, The water-spraying filler (7) is a discontinuous disturbance-type flow channel structure. Its matrix is ​​made of modified PVC material and the surface is integrally molded. It has multiple parallelogram protrusions (701). The acute angle of the parallelogram protrusions (701) is 30°-45°, the height is 8-15 mm, the distance between adjacent protrusions is 20-30 mm, and a disturbance channel (702) is formed between the protrusions.

5. The air dehumidification, cooling, and thermosiphon water recovery system according to claim 4, characterized in that, The circulating water spraying assembly (5) includes a water supply pipe (501), a nozzle (502), and a filter plate (503). The water supply pipe (501) is a ring-shaped stainless steel pipe network structure. The nozzle (502) is a spiral atomizing nozzle and is evenly distributed on the ring-shaped pipe network. The spraying angle of the nozzle (502) is 70°-120°, and the overlap rate of the spraying coverage area of ​​adjacent nozzles is not less than 30%. The filter plate (503) is located on the top of the water collection tank (8), is made of stainless steel, and has a filtration accuracy of 1-2 mm. The filter plate (503) is detachably connected to the inner wall of the water collection tank (8) by bolts.

6. The air dehumidification, cooling, and thermosiphon water recovery system according to claims 1-5, characterized in that, The thermosiphon array (3) is located 0.5 m to 1.0 m above the water collector (4), arranged symmetrically on both sides in a single row at an inclination of 20°-45°. It consists of 1000 thermosiphons fixed by a bracket. The inner and outer diameters of a single thermosiphon are 18.5 mm and 20 mm, respectively, and the tube spacing is 40 mm. It includes a thermosiphon condensation section (301), a thermosiphon insulation section (302), and a thermosiphon evaporation section (303). The thermosiphon evaporation section (303) is located in the humid and hot airflow above the water collector in the tower. The thermosiphon condensation section (301) extends to the outside of the tower body (1) and is exposed to the ambient air. The thermosiphon insulation section (302) is located at the tower wall of the tower body (1) and is fixed to the wall. The working fluid inside the tube is distilled water. The hot and humid air inside the tower is cooled as it flows through the thermosiphon evaporation section (303), and the temperature drops below the dew point. Some of the water vapor it contains condenses into liquid water and falls back into the water collection pool (8).

7. The air dehumidification, cooling, and thermosiphon water recovery system according to claim 6, characterized in that, The wind deflector assembly (6) includes a drive component (601), a rotating shaft (602), and a wind deflector (603). The drive component (601) mainly includes a servo motor. The rotating shaft (602) is arranged radially along the tower body (1) and is connected to the drive component (601) through a bearing. The wind deflector (603) is an arc-shaped plate structure and is connected to the rotating shaft (602) through bolts.

8. A method for air dehumidification cooling and thermosiphon water recovery using the air dehumidification cooling and thermosiphon water recovery system as described in claim 7, characterized in that, include: Air dehumidification pretreatment: Ambient air enters the dehumidifier through the air duct. The dehumidifier uses a calcium chloride salt solution with a mass fraction of 30% to 45% as the dehumidification medium. The solution is delivered to the dehumidification liquid nozzle through the dehumidification liquid inlet. The dehumidification liquid nozzle is evenly arranged along the direction of the air duct so that the dehumidification liquid forms a uniform liquid film or fine droplets. In the circulating water evaporative cooling process, circulating water from the power plant condenser is transported through pipelines to the circulating water spray assembly. It is first atomized into fine water droplets of 50-200 µm by nozzles and evenly sprayed onto the water-spraying packing. The atomized water droplets flow downwards through the water-spraying packing, while the dehumidified dry air flows upwards in the opposite direction, creating a gas-liquid mixture. The cooled circulating water falls into the collection pool at the bottom of the tower and is filtered through a filter plate to remove impurities before being returned to the power plant condenser for reuse. The air, having absorbed heat and moisture, continues to flow upwards, entering the subsequent humid air moisture thermosiphon condensation and recovery process. The high-temperature and high-humidity air generated during the evaporation and cooling process of circulating water first passes through a water collector to initially separate the entrained water droplets, and then flows through a thermosiphon array located 0.5 m to 1.0 m above the water collector. The thermosiphon array is arranged at an angle, with its evaporation section completely immersed in the humid and hot airflow above the water collector inside the tower. The condensation section of the thermosiphon extends to the outside of the tower body, and the insulation section of the thermosiphon is located at the tower wall and fixed to the wall surface. The tube is filled with distilled water solution as the heat transfer medium. When the humid air flows through the evaporation section of the thermosiphon, it comes into contact with the cool tube wall, and the water vapor in the air quickly condenses into liquid water on the tube wall and drips into the water collection pool under the action of gravity. Waste heat recovery is used to regenerate the dehumidifying fluid. After the calcium chloride solution absorbs moisture in the dehumidifier, its concentration decreases and it falls into the dehumidifying fluid collection tank. It is then transported from the dehumidifying fluid outlet to the regeneration fluid inlet of the dehumidifying fluid regenerator through a pipeline. There, it is atomized into fine water droplets by the regeneration fluid nozzles and sprayed evenly. This allows the low-concentration calcium chloride solution to fully contact the waste heat flue gas or low-pressure extraction steam collected from the power plant turbine by the waste heat flue gas recovery unit. At this temperature, the water in the dilute solution evaporates rapidly and is discharged from the waste heat flue gas outlet with the flue gas. The mass fraction of the calcium chloride solution gradually recovers to a high hygroscopic state of 30% to 45%. The regenerated calcium chloride solution is collected in the regeneration fluid collection tank and discharged through the regeneration fluid outlet. Then, driven by a high-pressure pump, it is transported to the dehumidifying fluid inlet of the dehumidifier. After being sprayed by the dehumidifying fluid nozzles, it participates in the air dehumidification process again, realizing the closed-loop regeneration and recycling of the dehumidifying fluid.

9. A cooling tower, characterized in that... Includes the air dehumidification and cooling and thermosiphon water recovery system as described in any one of claims 1-7.

10. A power plant, characterized in that... Including the cooling tower as described in claim 9.

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