Greenhouse salt water desalination system capable of realizing all-day operation

Abstract

The utility model discloses a greenhouse salt water desalination system capable of realizing all-day operation, and belongs to the technical field of brackish water desalination and greenhouse planting. The system comprises an adjustable shutter arranged at an inlet of the greenhouse, a first wet curtain, a humidifying device, a condenser, a dehumidification dry curtain, a multi-stage heat storage water tank, a cold water tank and a fresh water tank, the first wet curtain, the humidifying device, the condenser and the dehumidification dry curtain are sequentially arranged in the greenhouse, and the multi-stage heat storage water tank, the cold water tank and the fresh water tank are arranged outside the greenhouse. The multi-stage heat storage water tank comprises a first-stage water tank, a second-stage water tank, a third-stage water tank and a fourth-stage water tank, the system realizes day-and-night operation of the brackish water greenhouse desalination system, and provides suitable environmental conditions for night growth of crops in the greenhouse. According to the outdoor temperature, condensed and dehumidified air is selectively and directly fed into a crop area in the greenhouse or returns to a first wet curtain inlet on the west side of the greenhouse to be mixed with fresh air, day and night operation of the system in summer and spring and autumn is achieved, and the growth cycle of crops is shortened by additionally arranging a light supplementing lamp at night.

Description

Technical Field

[0001] The utility model relates to a greenhouse salt water desalination system which can realize all-day operation, and belongs to the technical field of brackish water desalination and greenhouse planting. Background Art

[0002] In traditional agricultural production, large-scale water and soil development and energy consumption have brought huge challenges to agricultural land and energy use. Saline-alkali land is an important reserve arable land resource in my country, and is mainly distributed in the northwest, north China and northeast China, with a total area of ​​more than 500 million mu. Efficient use of saline-alkali land and development of brackish water desalination for the development of green agriculture are of great significance to the realization of sustainable ecological development.

[0003] Solar greenhouses can save water and land, and increase crop yields. They are a modern agricultural planting method with complete independent property rights and huge production scale in my country. They have the strong advantage of not needing heating (or less heating) in winter to ensure the safety of crops overwintering, and are widely used in northern China. However, the special insulation wall structure of solar greenhouses limits the planting of greenhouse crops in summer. Under high temperature conditions during the day, the greenhouse needs to adopt special technical means for ventilation and cooling to meet the temperature and humidity requirements for crop growth in the greenhouse. In summer nights, due to the lack of solar radiation and relatively low outdoor air temperature, the temperature difference between day and night in the spring and autumn seasons in the north will further increase. The existing brackish water greenhouse desalination system cannot meet the temperature and humidity requirements suitable for crop growth. At the same time, the water production efficiency is low, and the comfortable air after condensation and dehumidification is directly discharged, resulting in a waste of air cooling. Therefore, a new technical method is urgently needed to ensure that the brackish water greenhouse desalination system can operate day and night in summer and spring and autumn, and to cool or keep warm according to the outdoor temperature to maintain the temperature and humidity suitable for crop growth in the greenhouse, while meeting the fresh water demand to achieve all-weather operation of the system.

[0004] A Chinese patent document with publication number CN113875461A discloses a brackish water desalination system suitable for summer greenhouses. The system couples greenhouse ventilation and cooling with fresh water production technology to achieve ventilation and cooling of the greenhouse in summer while desalinating salt water. However, the system is limited to greenhouse ventilation and salt water desalination under high temperature conditions in summer, and cannot achieve targeted greenhouse warmth at night. The existing brackish water greenhouse desalination system can only use outdoor sunlight or high temperature during the day to make the air have a larger water holding capacity, and absorb moisture from the humidification device and crop transpiration to enter the condenser for dehumidification and water production. However, at night, due to the lack of solar radiation and the relatively low outdoor air temperature, the temperature conditions for crop growth in the greenhouse cannot be met and effective dehumidification and water production cannot be achieved. Utility Model Content

[0005] In order to overcome the deficiencies of the prior art, the utility model proposes a greenhouse salt water desalination system that can be operated all day long. The operation mode of the system is regulated according to outdoor environmental parameters, so that the desalination system can be operated day and night and produce fresh water. The residual heat of the brackish water after humidification and concentration during the day is fully utilized, a heat storage tank is set up to store the high-temperature brackish water after humidification and concentration during the day, and a wet curtain humidification device with a heat exchanger is designed as a secondary humidification device. At night, the high-temperature brackish water in the heat storage tank is drawn into the heat exchanger for heat exchange. At the same time, the air temperature at the wet curtain inlet is increased to increase the water holding capacity of the air, thereby increasing the condensation dehumidification water production; in addition, the return air mode is regulated according to the outdoor temperature to ensure that the greenhouse has a suitable temperature and humidity at night, so that the greenhouse desalination system can produce water at night, and the system can be operated all day long.

[0006] The utility model adopts the following technical solution: a greenhouse salt water desalination system that realizes all-day operation includes an adjustable shutter arranged at the entrance of a greenhouse, a first wet curtain, a humidifying device, a condenser, a dehumidifying dry curtain arranged in sequence inside the greenhouse, and a multi-stage hot water storage tank, a cold water tank and a fresh water tank arranged outside the greenhouse, the humidifying device includes a coil heat exchanger and a second wet curtain, and the multi-stage hot water storage tank includes a first water tank, a second water tank, a third water tank and a fourth water tank that are insulated and connected in sequence.

[0007] The cold water tank, the first water pump, the condenser, the condensate outlet pipe, the first branch pipe and the fourth-stage water tank are sequentially connected to form a closed loop, and the condensate outlet pipe is connected to the fourth-stage water tank through the second branch pipe and the second wet curtain, the third branch pipe and the first wet curtain respectively.

[0008] The water outlet of the primary water tank is connected to the water inlet of the coil heat exchanger through the second water pump, and the water outlet of the coil heat exchanger is connected to the third branch pipe through the fourth branch pipe and connected to the water inlet of the primary water tank through the fifth branch pipe.

[0009] The water spraying plate arranged at the bottom of the condenser is connected to the fresh water tank, a first valve is arranged on the pipe section between the first branch pipe and the second branch pipe on the third branch pipe, and a second valve is arranged on the fourth branch pipe.

[0010] The induced draft fan arranged on the right side of the dehumidification drying curtain is connected to the return air outlet of the greenhouse through the return air duct, and the return air duct is connected to the exhaust branch pipe and multiple supply air branch pipes.

[0011] Specifically, the adjustable shutters are arranged at the air inlet on the west side of the greenhouse, the induced draft fan is arranged on the east side of the greenhouse, the air outlet of the induced draft fan is connected to the return air duct, the return air duct is respectively connected to the dehumidified air supply outlet on the south side of the greenhouse through a plurality of air supply branches, and an air supply branch valve is installed on the air supply branch. An air supply valve is arranged on the return air duct near the west side of the greenhouse, the exhaust branch is connected to the pipe section on the left side of the air supply valve on the return air duct, a return air valve is arranged on the return air duct near the return air outlet, and an exhaust window is arranged on the north side of the greenhouse.

[0012] Specifically, a roller is installed at the bottom of the humidifying device. When the temperature of the air sent into the crop area in the greenhouse is relatively high, the humidifying device can be moved to the west side of the greenhouse; when the air temperature and humidity in the crop area in the greenhouse are suitable for crop growth, the humidifying device can be moved to the east side of the greenhouse close to the condenser to increase water production.

[0013] Beneficial effects of the utility model:

[0014] (1) The brackish water greenhouse desalination system can be operated day and night, providing suitable environmental conditions for the nighttime growth of crops in the greenhouse. Depending on the outdoor temperature, the condensed and dehumidified air is selectively sent directly into the crop area in the greenhouse or returned to the first wet curtain entrance on the west side of the greenhouse to mix with the fresh air, so that the brackish water greenhouse desalination system can be operated day and night in summer and spring and autumn. By adding supplementary lighting at night, the growth cycle of crops can be further shortened.

[0015] (2) The high-temperature brackish water at the condenser outlet and after humidification with the wet curtain when the system is running during the day is stored in a multi-stage heat storage tank, and is used to heat the air in the coil heat exchanger, so that the air can take away more moisture when passing through the second wet curtain in the humidification device; at the same time, a portion of the high-temperature brackish water in the multi-stage heat storage tank can be used for spray humidification of the first wet curtain and the second wet curtain in the humidification device, which can increase the temperature of the cold air entering the room from the outside, thereby realizing and enhancing the system's nighttime water production. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of a greenhouse salt water desalination system that can operate around the clock.

[0017] Figure 2 The working principle diagram of a greenhouse salt water desalination system that can operate around the clock.

[0018] Figure 3 The present invention is a daytime working principle diagram of a greenhouse salt water desalination system that realizes full-day operation.

[0019] Figure 4 The present invention is a night working principle diagram of a greenhouse salt water desalination system that realizes full-day operation.

[0020] In the figure: 1, adjustable shutter, 2, first wet curtain, 2a, first sprinkler pipe, 3, humidifying device, 3a, coil heat exchanger, 3b, second wet curtain, 3c, fourth branch pipe, 3d, fifth branch pipe (3d), 4, condenser, 4a, condensate outlet pipe, 4b, first branch pipe, 4c, second branch pipe, 4d, third branch pipe, 5, dehumidification dry curtain, 6, multi-stage hot water storage tank, 6a, first water tank, 6d, second water tank, 6d, third water tank, 6d, fourth water tank, 7, cold water tank, 8, fresh water tank, 9, first water pump, 10, second water pump, 11, first valve, 12, second valve, 13, induced draft fan, 14, return air duct, 15, return air outlet, 16, supply air branch pipe, 17, exhaust air branch pipe, 18, supply air valve, 19, return air valve. DETAILED DESCRIPTION

[0021] In order to make the technical solutions, basic features and functions achieved by the utility model clear and understandable, the solutions of the utility model are further specifically and completely described below through embodiments and in combination with the accompanying drawings.

[0022] Figure 1 and 2 The schematic diagram of the structure of a greenhouse desalination system that can be operated all day is shown. In the figure, the greenhouse desalination system that can be operated all day includes an adjustable shutter 1 arranged at the entrance of the greenhouse, a first wet curtain 2, a humidifying device 3, a condenser 4, a dehumidifying dry curtain 5 arranged inside the greenhouse from west to east, and a multi-stage hot water storage tank 6, a cold water tank 7 and a fresh water tank 8 arranged outside the greenhouse. The humidifying device 3 includes a coil heat exchanger 3a and a second wet curtain 3b. The multi-stage hot water storage tank 6 includes a primary water tank 6a, a secondary water tank 6b, a tertiary water tank 6c and a quaternary water tank 6d connected in sequence through water pipes. An insulation layer is provided between adjacent water tanks, and valves are provided on the water pipes connecting adjacent water tanks. The water outlet of the cold water tank 7 is connected to the condensate inlet of the condenser 4 through the first water pump 9, the condensate outlet pipe 4a of the condenser is connected to the water inlet of the fourth water tank 6d and the cold water tank 7 in sequence through the first branch pipe 4b, the condensate outlet pipe 4a is connected to the first wet curtain 2, the water spraying plate at the bottom of the first wet curtain 2, the first water spraying pipe 2a, and the first branch pipe 4b in sequence through the third branch pipe 4d, and is connected to the second wet curtain 3b, the water spraying plate at the bottom of the second wet curtain 3b and the first water spraying pipe 2a in sequence through the second branch pipe 4c; the water outlet of the primary water tank 6a is connected to the water inlet of the coil heat exchanger 3a through the second water pump 10, the water outlet of the coil heat exchanger 3a is connected to the third branch pipe 4d through the fourth branch pipe 3c, and is connected to the water inlet of the primary water tank 6a through the fifth branch pipe 3d. The water spray tray arranged at the bottom of the condenser 4 is connected to the fresh water tank 8, a first valve 11 is arranged on the pipe section between the first branch pipe 4b and the second branch pipe 4c on the third branch pipe 4d, and a second valve 12 is arranged on the fourth branch pipe.

[0023] The induced draft fan 13 arranged on the right side of the dehumidification drying curtain 5 is connected to the return air outlet 15 of the greenhouse through the return air duct 14, and the return air duct 14 is connected to the exhaust branch pipe 17 and multiple supply air branch pipes 16.

[0024] The adjustable blinds 1 are arranged at the air inlet on the west side of the greenhouse, the induced draft fan 13 is arranged on the east side of the dehumidification drying curtain 5 in the greenhouse, the air outlet of the induced draft fan 13 is connected to the return air duct 14, and the return air duct 13 is respectively connected to the dehumidification air supply outlet on the south side of the greenhouse through multiple air supply branches 16, and the air supply branch pipes are equipped with air supply branch pipe valves. An air supply valve 18 is arranged on the return air duct near the west end of the greenhouse, the exhaust branch pipe 17 is connected to the pipe section on the left side of the air supply valve 18 on the return air duct, and a return air valve 19 is arranged on the return air duct near the return air outlet, and an exhaust window is arranged on the north side of the greenhouse.

[0025] The operation process of this greenhouse desalination system that operates all day is as follows:

[0026] 1. Daytime

[0027] During the day, the second valve 12 is closed, the coil heat exchanger does not work, and the adjustable shutter 1 is fully opened, and the air supply valve 18 is closed. The underground brackish water with a temperature of 15-20°C in the cold water tank 7 is sent to the condensing water pipe of the condenser 4 by the first water pump 9, absorbing the heat of the air outside the pipe. The brackish water with a temperature of 23-30°C after preheating enters the first branch pipe 4b, the second branch pipe 4c and the third branch pipe 4d from the outlet pipe 4a. The flow of the brackish water entering the first wet curtain 2, the second wet curtain 3b and directly returning to the fourth-stage water tank in the multi-stage hot water storage tank 6 is controlled by adjusting the first valve 11. The brackish water entering the first wet curtain 2 and the second wet curtain 3b humidifies and cools the air respectively. After heating and concentration, the brackish water with a temperature of 26-35°C flows from the water spraying plate at the bottom of the first wet curtain 2 and the water spraying plate at the bottom of the second wet curtain 3b into the fourth-stage water tank 6d, and part of the brackish water in the multi-stage hot water storage tank 6 returns to the cold water tank 7. The humid air outside the condenser tube is condensed into water on the surface of the vertical tube. The condensed water is collected in the watering tray at the bottom and then flows into the fresh water tank 8 through the pipeline for crop irrigation.

[0028] Under the action of the induced draft fan 13, the hot air with a temperature of 28-38°C passes through the adjustable shutter 1 and enters the first wet curtain 2. After exchanging heat with the brackish water with a temperature of 23-30°C in the first wet curtain 2, the temperature is reduced to 25-29°C, and the relative humidity is increased to 70%-90%; the cooled and humidified wet air flows through the air layer above the crops, absorbs heat and raises the temperature by 2-5°C, and the humidity is reduced to 60%-85%; the wet air flowing through the crop area enters the second wet curtain 3b in the humidification device, and the temperature is further reduced to 24-26°C, and the humidity is further increased to 9 5% or more; after being humidified by the second wet curtain 3b, the nearly saturated air is condensed and dehumidified to produce fresh water. After producing water, the cool air with a temperature of 22~25℃ enters the dehumidification dry curtain 5, so that the relative humidity of the air is further reduced to 40%~60%; driven by the induced draft fan 13, the air with suitable temperature and humidity is sprayed into the crop area in the greenhouse from the air supply port on the south side of the greenhouse through the return air duct 14 and the air supply branch 16. The comfortable air with a temperature of 22~25℃ and a relative humidity of 40%~60% flows along the crop canopy and is discharged to the external environment from the exhaust window on the north side of the greenhouse.

[0029] There are rollers at the bottom of the humidifier. When the air temperature sent into the crop area in the greenhouse is relatively high, the humidifier can be moved to the west side of the greenhouse. When the air temperature and humidity in the crop area in the greenhouse are suitable for crop growth, the humidifier can be moved to the east side of the greenhouse close to the condenser to increase water production.

[0030] The brackish water in the multi-stage water storage tank absorbs heat and heats up for a long time during the day through condensation dehumidification and wet curtain humidification, and the temperature can reach 30-35°C. The excess brackish water is connected to the cold water tank 7 through the brackish water pipe.

[0031] 2. Night

[0032] The system of the utility model can ensure that the brackish water greenhouse desalination system continues to operate at night, so that the greenhouse maintains a suitable temperature and humidity environment, thereby shortening the crop growth cycle and achieving nighttime water production. The first valve 11 is closed, the second valve 12 is opened, and the second water pump 10 sequentially and separately extracts the hot brackish water stored in each water tank in the multi-stage water storage tank 6. The hot brackish water at the outlet of the second water pump 10 is divided into two paths: one branch is connected to the coil heat exchanger 3a in the humidifying device to heat the air entering the humidifying device, and the hot brackish water after the temperature is reduced by 3~8℃ returns to the multi-stage water storage tank 6; the other branch is connected to the third branch 4d through the fourth branch pipe 3c, which is used for the first wet curtain 2 and the second wet curtain 3b to humidify the air, and the concentrated hot brackish water is returned to the multi-stage water storage tank 6 after the temperature is reduced by 2~5℃. During the day, the cold brackish water stored in the multi-stage water storage tank 6 after cooling at night flows into the cold water tank 7, and the cycle is repeated.

[0033] At night, the first water pump 9 draws brackish water with a temperature of about 15°C from the cold water tank and sends it into the condenser tube of the condenser. The brackish water, after absorbing heat and rising by 3~5°C, flows from the condensation water outlet into the fourth-stage water tank 6d of the multi-stage hot water storage tank 6, and the fourth-stage water tank 6d is directly connected to the cold water tank 7.

[0034] When the outdoor temperature at night is 17-28℃, which is suitable for crop growth, the adjustable shutters 1 and the air supply valve 18 are opened, and the exhaust window of the greenhouse, the air valve on the air supply branch pipe 16 and the return air valve 19 are closed. The air at 17-25℃ from the outside environment passes through the adjustable shutters 1 on the west side of the greenhouse and enters the first wet curtain 2 to exchange heat and moisture with the hot brackish water at a temperature of 30-35℃. The flow of the hot brackish water entering the first wet curtain 2 can be adjusted according to the temperature and humidity of the outdoor air; after heat exchange through the first wet curtain 2, the humid air with a temperature of 17-22℃ and a relative humidity of 40%-70% enters the planting area in the greenhouse. Since there is no solar radiation at night, the supplementary light is turned on to accelerate crop growth by photosynthesis of crops. In the process of air flowing from west to east in the greenhouse, it absorbs the moisture dissipated by crop respiration, and the temperature decreases by 0-2℃, and the relative humidity increases. Add 5%~10%; after the humid air cooled by the greenhouse passes through the coil heat exchanger 3a in the humidifying device and exchanges heat with hot brackish water, the air temperature rises by 2~5℃. At this time, the water holding capacity of the air is enhanced, and the air heated again enters the second wet curtain 3b for humidification, taking away more moisture and becoming nearly saturated humid air with a temperature of 17~21℃ and a relative humidity of more than 95%; the nearly saturated humid air enters the condenser 4 to produce condensed water on the surface of the condenser tube, and the humidity of the air after dehumidification and cooling is further reduced after absorbing moisture through the dehumidification dry curtain 5, and is directly discharged to the outdoor environment through the return air duct 14 through the exhaust branch pipe 17 under the action of the induced draft fan 13.

[0035] When the outdoor temperature at night is higher than 28°C, the same operation mode as that during the day is adopted. The comfortable air after condensation and dehumidification enters the crop area through the induced draft fan 13, the return air duct 14, and multiple air supply branches 16. The comfortable air attached to the crop canopy takes away the moisture dissipated by the crops' breathing and is discharged from the exhaust window on the north side of the greenhouse.

[0036] When the outdoor temperature is lower than 17°C at night, the adjustable louver 1 is adjusted to control the amount of fresh air entering from the outside, the return air valve 19 is opened, and the air valves on the multiple air supply branches 16 are closed at the same time. The opening of the return air valve 19 is regulated according to the outdoor air temperature, so that the humid air with a temperature of 18~22°C and a relative humidity of 40%~60% after condensation and dehumidification is sent to the inlet side of the first wet curtain 2 through the return air duct 14 and the return air port 15, and mixed with the outdoor cold air passing through the adjustable louver 1. The excess dehumidified air is discharged to the outside through the exhaust branch 17, and the flow rate of the dehumidified air discharged to the outside is equal to the flow rate of the cold air entering the greenhouse. The air with a temperature of 17~20°C after mixing enters the first wet curtain 2 for humidification, and the humidification water volume of the first wet curtain 2 is adjusted according to the relative humidity of the air at the inlet of the first wet curtain 2. When the relative humidity of the air at the inlet of the first wet curtain 2 has reached 70%, the flow rate of the brackish water entering the first wet curtain 2 is closed to prevent the excessive relative humidity in the greenhouse from causing crop diseases and insect pests. The air passing through the first wet curtain 2 takes away the moisture dissipated by the crops in the greenhouse during its flow from west to east. After the temperature drops by 0~2℃, it enters the coil heat exchanger 3a in the humidification device for heat exchange. After the air temperature rises by 4~7℃, it directly enters the second wet curtain 3b for humidification. The heated humid air can absorb more moisture in the second wet curtain and reach a nearly saturated state; then it enters the condenser for dehumidification and water production, and the above process is repeated for the comfortable air after condensation and dehumidification.

Claims

1. A greenhouse desalination system capable of operating all day, comprising an adjustable shutter (1) arranged at the entrance of the greenhouse, a first wet curtain (2) arranged in sequence inside the greenhouse, a humidifying device (3), a condenser (4), a dehumidifying dry curtain (5), and a multi-stage hot water storage tank (6), a cold water tank (7) and a fresh water tank (8) arranged outside the greenhouse, characterized in that: The humidifying device (3) comprises a coil heat exchanger (3a) and a second wet curtain (3b), and the multi-stage water storage tank (6) comprises a primary water tank (6a), a secondary water tank (6b), a tertiary water tank (6c), and a quaternary water tank (6d) which are sequentially thermally insulated and connected; The cold water tank (7), the first water pump (9), the condenser (4), the condensate outlet pipe (4a), the first branch pipe (4b) and the fourth-stage water tank (6d) are connected in sequence to form a closed loop, and the condensate outlet pipe (4a) is connected to the fourth-stage water tank (6d) via the second branch pipe (4c) and the second wet curtain (3b), the third branch pipe (4d) and the first wet curtain (2), respectively; The water outlet of the primary water tank (6a) is connected to the water inlet of the coil heat exchanger (3a) via the second water pump (10); the water outlet of the coil heat exchanger (3a) is connected to the third branch pipe (4d) via the fourth branch pipe (3c), and is connected to the water inlet of the primary water tank (6a) via the fifth branch pipe (3d); A water spray tray provided at the bottom of the condenser (4) is connected to a fresh water tank (8); a first valve (11) is provided on a pipe section of the third branch pipe (4d) between the first branch pipe (4b) and the second branch pipe (4c); and a second valve (12) is provided on the fourth branch pipe; The induced draft fan (13) disposed on the right side of the dehumidification drying curtain (5) is connected to the return air outlet (15) of the greenhouse via the return air duct (14), and the return air duct (14) is connected to the exhaust branch pipe (17) and a plurality of supply air branch pipes (16).

2. A greenhouse salt water desalination system capable of operating all day according to claim 1, characterized in that: The four water tanks in the multi-stage heat storage tank are connected by water pipes, a heat insulation layer is arranged between adjacent water tanks, and valves are arranged on the water pipes connecting adjacent water tanks.

3. A greenhouse salt water desalination system capable of operating all day according to claim 1, characterized in that: The first wet curtain (2) and the humidifying device (3) are respectively connected to the fourth-level water tank (6d) via a water spraying tray provided at the bottom.

4. A greenhouse salt water desalination system capable of operating all day according to claim 1, characterized in that: The humidifying device (3) is a movable humidifying device.

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