Purified water preparation system

Abstract

The utility model relates to a purified water preparation system which comprises pretreatment equipment, a pretreatment water tank, multi-stage reverse osmosis membrane equipment, electrodeionization equipment and a purified water tank which are sequentially communicated, and further comprises water-saving equipment, medicine washing equipment and a liquid storage tank, when the liquid storage tank is in a first working state, the liquid inlet and return port is communicated with a concentrated water side or a water production side of the multi-stage reverse osmosis membrane equipment, when the liquid storage tank is in a first working state, the liquid inlet and return port is communicated with the concentrated water side of the multi-stage reverse osmosis membrane equipment, and the water-saving equipment is communicated with the second liquid outlet and the pretreatment water tank; when the liquid storage tank is in a second working state, the liquid inlet and return port is communicated with the water production side of the multi-stage reverse osmosis membrane equipment, and the first liquid outlet is communicated with the chemical washing equipment. The liquid storage tank is used as a chemical washing tank and a concentrated water recovery tank, one tank has two purposes, the occupied space is small, chemical washing equipment and water-saving equipment are combined into an original purified water preparation system in a limited transformation space, and the transformation cost is saved.

Description

Technical Field

[0001] This utility model relates to the field of purified water preparation technology, and in particular to a purified water preparation system. Background Technology

[0002] The purified water preparation system within the plant includes a sand filter, an ultrafiltration unit, a reverse osmosis unit, and an electro-deionization unit. Raw water is sequentially treated through these units to produce purified water for use. During the purified water preparation process, wastewater is directly discharged without recycling, resulting in a low conversion rate. Furthermore, the system is prone to clogging after prolonged use due to the accumulation of residues, requiring cleaning with chemical washing equipment. Therefore, it is necessary to add chemical washing and water-saving equipment to the current purified water preparation system to clean residues and improve the conversion rate. However, the current purified water preparation system has limited space for future modifications, making it challenging to organically integrate the chemical washing and water-saving equipment within this limited space.

[0003] Therefore, there is an urgent need for a purified water preparation system to solve the above-mentioned technical problems. Utility Model Content

[0004] The purpose of this invention is to provide a system for preparing purified water, so as to solve at least one of the above-mentioned problems.

[0005] To achieve the above objectives, this utility model provides a purified water preparation system comprising a pretreatment device, a pretreatment water tank, a multi-stage reverse osmosis membrane device, an electro-deionization device, and a purified water tank, which are connected in sequence. The purified water preparation system further includes:

[0006] The liquid storage tank includes a liquid inlet / return port, a first liquid outlet, and a second liquid outlet. The liquid inlet / return port can be selectively connected to the concentrate side or the product water side of the multi-stage reverse osmosis membrane equipment.

[0007] A water-saving device is installed between the second liquid outlet and the pre-treated water tank;

[0008] A chemical cleaning device is disposed between the storage tank and the multi-stage reverse osmosis membrane device, and between the storage tank and the pretreatment device. The chemical cleaning device is capable of forward cleaning the multi-stage reverse osmosis membrane device and the pretreatment device.

[0009] The storage tank has a first working state and a second working state. When the storage tank is in the first working state, the inlet return port is connected to the concentrate side of the multi-stage reverse osmosis membrane device, and the water-saving device is connected to the second outlet and the pre-treated water tank respectively. When the storage tank is in the second working state, the inlet return port is connected to the product water side of the multi-stage reverse osmosis membrane device, and the first outlet is connected to the chemical washing device.

[0010] Furthermore, the pretreatment water tank is equipped with a liquid level detector, which can detect the liquid level in the pretreatment water tank.

[0011] Furthermore, the water-saving equipment includes a water-saving reverse osmosis membrane device and a filter. The water-saving reverse osmosis membrane device has a water-saving inlet side, a water-saving product side, and a water-saving concentrate side. The water-saving inlet side can be connected to the second liquid outlet. The water-saving product side is connected to the pre-treated water tank. The filter is connected to the water-saving concentrate side and the water-saving inlet side, respectively.

[0012] Furthermore, the water-saving device also includes a tank for storing scale inhibitor, which is connected to the water-saving inlet side.

[0013] Furthermore, the water-saving device also includes a high-pressure pump, which is connected to the second liquid outlet and the water-saving inlet side, respectively.

[0014] Furthermore, the water-saving device also includes a water-saving control valve, which is located on the connecting pipeline between the high-pressure pump and the second liquid outlet.

[0015] Furthermore, the multi-stage reverse osmosis membrane equipment includes a first-stage reverse osmosis membrane device and a second-stage reverse osmosis membrane device connected in sequence. The first-stage reverse osmosis membrane device is connected to the pretreatment water tank, and the second-stage reverse osmosis membrane device is connected to the electro-deionization equipment. The chemical cleaning equipment is capable of forward cleaning the first-stage reverse osmosis membrane device.

[0016] Furthermore, the first-stage reverse osmosis membrane device has a first-stage inlet water side, a first-stage product water side, and a first-stage concentrate water side. The first-stage inlet water side can be connected to the pretreatment water tank and the first outlet water port, respectively. The first-stage product water side can be connected to the second-stage reverse osmosis membrane device and the inlet return water port, and the first-stage concentrate water side can be connected to the inlet return water port.

[0017] Furthermore, the pretreatment equipment includes a sand filter and an ultrafiltration device connected together, the ultrafiltration device being connected to the pretreatment water tank, and the chemical washing device being able to clean the ultrafiltration device in the forward direction.

[0018] Furthermore, the chemical washing equipment includes a first chemical washing branch and a chemical washing circuit, the storage tank has a return port, the first chemical washing branch can be connected to the first outlet and the inlet of the ultrafiltration device respectively, and the chemical washing circuit can be connected to the outlet of the ultrafiltration device and the return port respectively.

[0019] The beneficial effects of this utility model are as follows:

[0020] The purified water preparation system provided by this utility model includes a pretreatment device, a pretreatment water tank, a multi-stage reverse osmosis membrane device, an electro-deionization device, and a purified water tank that are connected in sequence. The purified water preparation system also includes a water-saving device, a chemical washing device, and a storage tank. The chemical washing device is located between the storage tank and the multi-stage reverse osmosis membrane device, and between the storage tank and the pretreatment device, to forward clean the multi-stage reverse osmosis membrane device and the pretreatment device. The storage tank includes an inlet / outlet, a first outlet, and a second outlet. The outlet can be selectively connected to the concentrate side or the product water side of the multi-stage reverse osmosis membrane equipment. The water-saving device is located between the second outlet and the pretreatment water tank. The storage tank has a first working state and a second working state. When the storage tank is in the first working state, the inlet return outlet is connected to the concentrate side of the multi-stage reverse osmosis membrane equipment, and the water-saving device is connected to the second outlet and the pretreatment water tank respectively. When the storage tank is in the second working state, the inlet return outlet is connected to the product water side of the multi-stage reverse osmosis membrane equipment, and the first outlet is connected to the chemical washing equipment. When the storage tank is in its first operating state, the concentrated water obtained from the multi-stage reverse osmosis membrane equipment enters the storage tank through the inlet return port, and then enters the water-saving device through the second outlet. After being treated by the water-saving device, the concentrated water is added to the pretreatment water tank. Concentrated water that would otherwise be discharged is treated by the water-saving device and then re-enters the pretreatment water tank for purified water preparation, saving raw water and improving the conversion rate of purified water. When the storage tank is in its second operating state, the permeate obtained from the multi-stage reverse osmosis membrane equipment enters the storage tank through the inlet return port, and then enters the chemical washing equipment through the first outlet to perform forward cleaning of the multi-stage reverse osmosis membrane equipment and the pretreatment equipment, preventing blockage due to the accumulation of retentate. The storage tank can be used as both a chemical washing tank and a concentrated water recovery tank, serving two purposes in one, occupying little space. The chemical washing equipment and water-saving equipment can be integrated into the existing purified water preparation system within a limited modification space, saving modification costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the purified water preparation system provided in this embodiment of the utility model.

[0022] In the picture:

[0023] 1. Pretreatment equipment; 11. Sand filtration device; 12. Ultrafiltration device;

[0024] 2. Pretreatment water tank; 21. First preset liquid level; 22. Second preset liquid level;

[0025] 3. Multi-stage reverse osmosis membrane equipment; 31. First-stage reverse osmosis membrane unit; 311. First-stage feed water side; 312. First-stage product water side; 313. First-stage concentrate side; 32. Second-stage reverse osmosis membrane unit; 321. Second-stage feed water side; 322. Second-stage product water side;

[0026] 4. Electrodeionization equipment;

[0027] 5. Storage tank; 51. Liquid inlet / return port; 52. Return port; 53. First outlet; 54. Second outlet;

[0028] 101. Inlet pipe; 102. Main inlet and return pipe; 103. Branch inlet and return pipe; 104. Inlet valve; 105. Inlet and return valve;

[0029] 6. Chemical washing equipment; 61. Chemical washing pump; 62. Chemical washing main pipeline; 63. Chemical washing circuit; 64. Return valve; 65. First chemical washing control valve; 66. Second chemical washing control valve; 67. Chemical washing main valve; 68. First chemical washing branch; 69. Second chemical washing branch;

[0030] 7. Water-saving equipment; 71. High-pressure pump; 72. Water-saving reverse osmosis membrane device; 721. Water-saving inlet side; 722. Water-saving product water side; 723. Water-saving concentrate side; 73. Filter; 74. Chemical tank; 75. Metering pump; 76. Discharge tank; 77. Water-saving control valve;

[0031] 8. Water pump;

[0032] 9. Switching equipment; 91. First switching valve; 92. Second switching valve; 93. Third switching valve;

[0033] 10. Purified water tank;

[0034] 01. Raw water tank. Detailed Implementation

[0035] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining this utility model and not for limiting it. Furthermore, it should be noted that, for ease of description, only the parts related to this utility model are shown in the accompanying drawings, not all of them.

[0036] This utility model defines certain directional terms. Unless otherwise stated, the directional terms used, such as "up", "down", "left", "right", "inner", and "outer", are used for ease of understanding and therefore do not constitute a limitation on the scope of protection of this utility model.

[0037] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0038] In the description of this utility model, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0039] like Figure 1As shown, this embodiment provides a purified water preparation system, including a pretreatment device 1, a pretreatment water tank 2, a multi-stage reverse osmosis membrane device 3, an electro-deionization device 4, and a purified water tank 10 that are connected in sequence. The purified water preparation system also includes a water-saving device 7, a chemical washing device 6, and a storage tank 5. The chemical washing device 6 is located between the storage tank 5 and the multi-stage reverse osmosis membrane device 3, and is located between the storage tank 5 and the pretreatment device 1 to positively clean the multi-stage reverse osmosis membrane device 3 and the pretreatment device 1. The storage tank 5 includes an inlet / outlet 51, a first outlet 53, and a second outlet 54. The return port 51 can be selectively connected to the concentrate side or the product water side of the multi-stage reverse osmosis membrane device 3. The water-saving device 7 is located between the second outlet 54 and the pretreatment water tank 2. The storage tank 5 has a first working state and a second working state. When the storage tank 5 is in the first working state, the inlet return port 51 is connected to the concentrate side of the multi-stage reverse osmosis membrane device 3, and the water-saving device 7 is connected to the second outlet 54 and the pretreatment water tank 2 respectively. When the storage tank 5 is in the second working state, the inlet return port 51 is connected to the product water side of the multi-stage reverse osmosis membrane device 3, and the first outlet 53 is connected to the chemical washing device 6. When the storage tank 5 is in its first operating state, the concentrated water obtained from the multi-stage reverse osmosis membrane equipment 3 enters the storage tank 5 through the inlet return port 51, and then enters the water-saving equipment 7 through the second outlet 54. After being treated by the water-saving equipment 7, the concentrated water is added to the pretreatment water tank 2. The concentrated water that should have been discharged is treated by the water-saving equipment 7 and then enters the pretreatment water tank 2 again for the preparation of purified water, saving raw water and improving the conversion rate of purified water. When the storage tank 5 is in its second operating state, the permeate obtained from the multi-stage reverse osmosis membrane equipment 3 enters the storage tank 5 through the inlet return port 51, and then enters the chemical washing equipment 6 through the first outlet 53 to perform forward cleaning of the multi-stage reverse osmosis membrane equipment 3 and the pretreatment equipment 1, preventing the accumulation of trapped substances and blockage. The storage tank 5 can be used as a chemical washing tank and a concentrated water recovery tank, serving two purposes in one tank, occupying little space. The chemical washing equipment 6 and the water-saving equipment 7 can be integrated into the original purified water preparation system within a limited modification space, saving modification costs.

[0040] Furthermore, the purified water preparation system also includes a raw water tank 01, which is connected to a raw water source and can be connected to the pretreatment equipment 1.

[0041] Furthermore, the purified water preparation system also includes a water pump 8, which is located between the raw water tank 01 and the pretreatment equipment 1.

[0042] Furthermore, the purified water preparation system also includes a switching device 9, which includes a first switching valve 91 located between the raw water tank 01 and the water pump 8. When the first switching valve 91 is closed, the raw water in the raw water tank 01 no longer flows to the pretreatment equipment 1.

[0043] Furthermore, the pretreatment equipment 1 includes a sand filter 11 and an ultrafiltration device 12 connected in sequence. The sand filter 11 is connected to the raw water tank 01, and the ultrafiltration device 12 is connected to the pretreatment water tank 2. The sand filter 11 removes suspended solids, colloids, microorganisms, and other impurities from the raw water through physical filtration and partial chemical adsorption. The ultrafiltration device 12 removes suspended solids, colloids, bacteria, viruses, and large molecular organic matter from the water treated by the sand filter 11 through physical sieving, while retaining ions and small molecules in the water.

[0044] Furthermore, the switching device 9 also includes a second switching valve 92, which is located on the connecting pipeline between the ultrafiltration device 12 and the pretreatment water tank 2. The second switching valve 92 can prevent water treated by the pretreatment device 1 from entering the pretreatment water tank 2.

[0045] Furthermore, the multi-stage reverse osmosis membrane equipment 3 includes a first-stage reverse osmosis membrane device 31 and a second-stage reverse osmosis membrane device 32 connected in sequence. The first-stage reverse osmosis membrane device 31 is connected to the pretreatment water tank 2, and the second-stage reverse osmosis membrane device 32 is connected to the electro-deionization equipment 4.

[0046] Furthermore, the switching device 9 also includes a third switching valve 93, which is located on the connecting pipeline between the electro-deionization device and the purified water tank 10. The combined use of the third switching valve 93 and the first switching valve 91 can shut off the main purified water preparation pipeline. The main purified water preparation pipeline includes the connecting pipeline between the raw water tank 01, the pretreatment device 1, the pretreatment water tank, the multi-stage reverse osmosis membrane device 3, the electro-deionization device 4, and the purified water tank 10.

[0047] In this embodiment, since the primary reverse osmosis membrane unit 31 and the ultrafiltration unit 12 are prone to clogging due to the accumulation of retained substances, the chemical cleaning device 6 only performs forward cleaning on the primary reverse osmosis membrane unit 31 in the multi-stage reverse osmosis membrane unit 3 and the ultrafiltration unit 12 in the pretreatment unit 1. This ensures the quality of the purified water while also achieving water conservation. Of course, in other embodiments, the multi-stage reverse osmosis membrane unit 3 and the pretreatment unit 1 can also be chemically cleaned as a whole.

[0048] Specifically, the first-stage reverse osmosis membrane unit 31 has a first-stage feed water side 311, a first-stage product water side 312, and a first-stage concentrate side 313. The second-stage reverse osmosis membrane unit 32 has a second-stage feed water side 321, a second-stage product water side 322, and a second-stage concentrate side. The first-stage product water side 312 is connected to the pretreatment water tank 2, the first-stage product water side 312 is connected to the second-stage feed water side 321, and the second-stage product water side 322 is connected to the electro-deionization equipment 4. In addition, the first-stage feed water side 311 can be connected to the first outlet 53, and both the first-stage product water side 312 and the first-stage concentrate side 313 can be connected to the inlet and outlet 51.

[0049] Furthermore, the purified water preparation system also includes an inlet pipe 101, an inlet-outlet return main pipe 102, and an inlet-outlet return branch pipe 103. One end of the inlet-outlet return main pipe 102 can be connected to the inlet pipe 101 and the inlet-outlet return branch pipe 103 respectively, and the other end is connected to the inlet-outlet return port 51 of the storage tank 5. The inlet pipe 101 can be connected to the primary product water side 312, and the inlet-outlet return branch pipe 103 can be connected to the primary concentrate side 313.

[0050] Furthermore, the purified water preparation system also includes an inlet valve 104, which is located on the inlet pipeline 101 and is used to control whether the water from the primary water production side 312 enters the storage tank 5.

[0051] Furthermore, the purified water preparation system also includes an inlet / outlet valve 105, which is installed on the inlet / outlet branch pipe 103. The inlet / outlet valve 105 is used to control whether the water on the primary concentrate side 313 enters the storage tank 5.

[0052] In this embodiment, the destination of the water on the secondary concentrate side is not limited; it can be directly discharged or recycled.

[0053] Furthermore, the chemical washing device 6 includes a first chemical washing branch 68 and a chemical washing circuit 63. The storage tank 5 has a return port 52. The first chemical washing branch 68 can be connected to the first outlet 53 and the inlet of the ultrafiltration device 12, respectively. The chemical washing circuit 63 can be connected to the outlet and the return port 52 of the ultrafiltration device 12, respectively. This arrangement allows the storage tank 5 and the ultrafiltration device 12 to form a circulation loop, so as to clean the ultrafiltration device 12 and prevent the ultrafiltration device 12 from being blocked by the accumulation of trapped substances.

[0054] Furthermore, the chemical washing equipment 6 also includes a first chemical washing control valve 65, which is located on the first chemical washing branch and is used to control whether to perform chemical washing on the ultrafiltration device 12.

[0055] Furthermore, the washing equipment 6 also includes a return valve 64, which is located on the washing circuit 63 and is used to control whether the water flowing through the ultrafiltration device 12 flows back into the storage tank 5.

[0056] Furthermore, the chemical washing equipment 6 also includes a second chemical washing branch 69, one end of which can be connected to the first outlet 53 of the storage tank 5, and the other end is connected to the first water inlet side 311.

[0057] Furthermore, the chemical washing equipment 6 also includes a second chemical washing control valve 66, which is located on the second chemical washing branch and is used to control whether to perform chemical washing on the first-stage reverse osmosis membrane unit 31.

[0058] Furthermore, the chemical washing equipment 6 also includes a chemical washing main pipeline 62, one end of which is connected to the first outlet 53 of the storage tank 5, and the other end is connected to the first chemical washing branch 68 and the second chemical washing branch 69 respectively.

[0059] Furthermore, the chemical washing equipment 6 also includes a chemical washing pump 61, which is installed on the main chemical washing pipeline 62. The chemical washing pump 61 can increase the flow rate of the chemical washing solution, and also increase the flow rate of flushing the membrane surface of the ultrafiltration device 12 and the first-stage reverse osmosis membrane device 31, thereby improving the flushing effect on the membrane surface retained substances, reducing the accumulation of fouling on the membrane surface, reducing membrane clogging, improving the stability of membrane operation, and extending the service life of the ultrafiltration device 12 and the first-stage reverse osmosis membrane device 31.

[0060] Furthermore, the chemical washing equipment 6 also includes a chemical washing main valve 67, which is located on the chemical washing main pipeline 62 and between the chemical washing pump 61 and the first outlet 53.

[0061] Furthermore, the water-saving device 7 includes a water-saving reverse osmosis membrane device 72 and a filter 73. The water-saving reverse osmosis membrane device 72 has a water-saving inlet side 721, a water-saving product side 722, and a water-saving concentrate side 723. The water-saving inlet side 721 can be connected to the second outlet 54, the water-saving product side 722 is connected to the pre-treated water tank 2, and the filter 73 is connected to both the water-saving concentrate side 723 and the water-saving inlet side 721. The concentrate produced from the first-stage reverse osmosis membrane device 31 enters the water-saving reverse osmosis membrane device 72 through the storage tank 5, and flows back to the water-saving inlet side 721 from the water-saving concentrate side 723, realizing two-round concentrate recycling, achieving the purpose of water saving and improving the conversion rate of purified water.

[0062] In this embodiment, the water-saving reverse osmosis membrane device 72 is the original reverse osmosis membrane device in the water treatment system, which reduces the transformation cost.

[0063] Furthermore, the water-saving device 7 also includes a discharge pool 76, which is connected to the water-saving concentrate side 723.

[0064] Furthermore, the water-saving device 7 also includes a chemical tank 74 storing a scale inhibitor, which is connected to the water-saving inlet side 721.

[0065] Specifically, the scale inhibitor can be a reverse osmosis scale inhibitor manufactured by DuPont Dow, model ACUMER™ 4200.

[0066] Furthermore, the water-saving device 7 also includes a metering pump 75, which is located on the connecting pipeline between the agent tank 74 and the water-saving inlet side 721. The metering pump 75 is used to control the flow rate of the agent entering the water-saving inlet side 721.

[0067] Furthermore, the water-saving device 7 also includes a high-pressure pump 71, which can be connected to the second liquid outlet 54 and the water-saving inlet side 721 respectively.

[0068] In this embodiment, the metering pump 75 and the high-pressure pump 71 operate simultaneously.

[0069] Furthermore, the water-saving device 7 also includes a water-saving control valve 77, which is located on the connecting pipeline between the high-pressure pump 71 and the second outlet 54. The water-saving control valve 77 is used to control whether the water in the storage tank 5 enters the water-saving device 7.

[0070] Furthermore, the pretreatment water tank 2 is equipped with a level detector, which can detect the liquid level in the pretreatment water tank 2. When the liquid level in the pretreatment water tank 2 reaches the first preset liquid level, the pretreatment water tank 2 is connected to the water-saving device 7, and the pretreatment water tank 2 is disconnected from the pretreatment device 1, that is, the second switch valve 92 is closed; when the liquid level in the pretreatment water tank 2 reaches the second preset liquid level, both the pretreatment device 1 and the water-saving device 7 are connected to the pretreatment water tank 2, that is, the second switch valve 92 is opened. The first preset liquid level is higher than the second preset liquid level. In other words, the water supply for the multi-stage reverse osmosis membrane unit 3 is provided by the water in the pretreatment water tank 2. The water in the pretreatment water tank 2 has two sources: the product water from the pretreatment unit 1 and the concentrate from the first-stage reverse osmosis membrane unit 31, which is then recycled by the water-saving device 7. When the liquid level in the pretreatment water tank 2 reaches the first preset level, only the concentrate from the first-stage reverse osmosis membrane unit 31, recycled by the water-saving device 7, enters the pretreatment water tank 2, and the pretreatment unit 1 does not operate. When the liquid level in the pretreatment water tank 2 reaches the second preset level, the pretreatment unit 1 operates, and both the product water from the pretreatment unit 1 and the concentrate from the first-stage reverse osmosis membrane unit 31, recycled by the water-saving device 7, enter the pretreatment water tank 2. This setup maximizes the utilization of the concentrate from the first-stage reverse osmosis membrane unit 31 recycled by the water-saving device 7, thereby improving the conversion rate of purified water.

[0071] Optionally, the liquid level detector can be an ultrasonic sensor. The ultrasonic sensor is located on the top of the pretreatment water tank 2. The ultrasonic sensor emits ultrasonic waves, which are reflected by the liquid surface during propagation to form an echo. The liquid level height can be calculated based on the time difference between the emission of the ultrasonic wave and the reception of the echo, thus obtaining the current liquid level of the pretreatment water tank 2.

[0072] Optionally, the level detector can also be a capacitive level sensor, a photoelectric level sensor, or a pressure sensor, which is installed on the inner side wall of the pretreatment tank 2. Furthermore, the above-mentioned level detector can also be installed at both the first preset level and the second preset level.

[0073] It should be noted that the first and second working states of the storage tank 5 do not occur simultaneously. When the storage tank 5 switches from the first working state to the second working state, the concentrated water in the storage tank 5 needs to be discharged first, and then the product water is introduced into the storage tank 5 from the first-stage water inlet side 311. A cleaning reagent is added to prepare an acid solution or an alkaline solution, and then the first-stage reverse osmosis membrane device 31 and / or ultrafiltration device 12 are positively cleaned.

[0074] In this embodiment, the conductivity of the water in the pretreatment tank 2 is the same as that of the raw water, approximately 200-400 μS / cm. The conductivity of the inlet water of the water-saving device 7 is approximately 1000-2000 μS / cm. While ensuring the water production of the water-saving device 7, the conductivity of the produced water is approximately 100-200 μS / cm, which meets the water quality requirements without requiring frequent cleaning of the water-saving device 7. The water-saving reverse osmosis membrane device 72 will only be cleaned when the water production of the water-saving device 7 significantly decreases.

[0075] The frequency of chemical washing for the ultrafiltration device 12 and the first-stage reverse osmosis membrane device 31 can be once every six months to ensure the quality of purified water preparation.

[0076] The installation of water-saving equipment 7 can save approximately 45,000 tons of pre-treated water and approximately 50,000 tons of raw water annually, while ensuring the production of purified water.

[0077] When the storage tank 5 is in its first working state, the first switching valve 91, the second switching valve 92, the third switching valve 93, the inlet and return valve 105, and the water-saving control valve 77 are open, while the inlet valve 104, the return valve 64, the main chemical washing valve 67, the first chemical washing control valve 65, and the second chemical washing control valve 66 are closed. The concentrated water obtained after treatment by the multi-stage reverse osmosis membrane equipment 3 enters the storage tank 5 through the inlet and return port 51, and then enters the water-saving equipment 7 through the second outlet 54. The concentrated water and the scale inhibitor in the chemical tank 74 are separated. After the agent is mixed, it enters the water-saving inlet side 721 of the water-saving reverse osmosis membrane device 72. The product water from the water-saving product water side 722 enters the pretreatment water tank 2. Part of the concentrate from the water-saving concentrate side 723 is discharged into the discharge pool 76, and the other part is filtered by the filter 73 and then re-enters the water-saving inlet side 721. The concentrate that should have been discharged from the first-stage reverse osmosis membrane device 31 is treated by the water-saving reverse osmosis membrane device 72 and then enters the pretreatment water tank 2 again, which is a two-round recycling process and improves the conversion rate of purified water.

[0078] When the storage tank 5 is in the second working state, the first switch valve 91, the second switch valve 92, the third switch valve 93, the inlet return valve 105, and the water-saving control valve 77 are closed, while the return valve 64 and the chemical cleaning main valve 67 are opened. First, the concentrated water in the storage tank 5 is discharged, and then the permeate water remaining in the first-stage reverse osmosis membrane device 31 is filled into the storage tank 5 from the first-stage inlet water side 311. Chemical cleaning reagents are added to prepare a chemical cleaning solution, which can be an acid solution or an alkaline solution. The inlet valve 104 is closed, the inlet return valve 105 is opened, and then the first-stage reverse osmosis membrane device 31 and / or the ultrafiltration device 12 are positively cleaned. The permeate obtained after treatment by the first-stage reverse osmosis membrane unit 31 enters the storage tank 5 through the inlet pipe 101, the inlet return pipe 102 and the inlet return port 51, and then enters the chemical washing equipment 6 through the first outlet 53, so as to perform forward cleaning of the first-stage reverse osmosis membrane unit 31 and the ultrafiltration unit 12 to prevent the accumulation of trapped substances and blockage. When the ultrafiltration unit 12 needs to be cleaned, the first chemical cleaning control valve 65 is opened. The chemical cleaning solution in the storage tank 5 enters the inlet of the ultrafiltration unit 12 through the first outlet 53, the main chemical cleaning pipeline 62, and the first chemical cleaning branch 68, and flows into the chemical cleaning circuit 63 from the outlet of the ultrafiltration unit 12, and then flows back into the storage tank 5. When the first-stage reverse osmosis membrane unit 31 needs to be cleaned, the second chemical cleaning control valve 66 is opened. The chemical cleaning solution in the storage tank 5 enters the first-stage inlet water side 311 of the first-stage reverse osmosis membrane unit 31 through the first outlet 53, the main chemical cleaning pipeline 62, and the second chemical cleaning branch 69, and flows into the inlet return branch pipeline 103 from the first-stage concentrate side 313 of the first-stage reverse osmosis membrane unit 31, and then flows back into the storage tank 5.

[0079] When the storage tank 5 is used as a water-saving tank, the inlet and return branch pipe 103 is used as an inlet pipe; when the storage tank 5 is used as a medicine washing tank, the inlet and return branch pipe 103 is used as a return pipe.

[0080] The purified water preparation system provided in this embodiment combines with the existing water treatment system, featuring a simple process, compact structure, small footprint, and low modification cost. Although the present invention has been described in detail above with general descriptions, specific embodiments, and experiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A purified water preparation system, comprising a pretreatment device (1), a pretreatment water tank (2), a multi-stage reverse osmosis membrane device (3), an electro-deionization device (4), and a purified water tank (10) connected in sequence, characterized in that, The purified water preparation system further includes: The storage tank (5) includes an inlet return port (51), a first outlet (53) and a second outlet (54), wherein the inlet return port (51) can be selectively connected to the concentrate side or the product water side of the multi-stage reverse osmosis membrane device (3). Water-saving device (7) is located between the second liquid outlet (54) and the pre-treated water tank (2); A chemical cleaning device (6) is provided between the liquid storage tank (5) and the multi-stage reverse osmosis membrane device (3), and between the liquid storage tank (5) and the pretreatment device (1). The chemical cleaning device (6) is capable of forward cleaning the multi-stage reverse osmosis membrane device (3) and the pretreatment device (1). The storage tank (5) has a first working state and a second working state. When the storage tank (5) is in the first working state, the liquid inlet return port (51) is connected to the concentrate side of the multi-stage reverse osmosis membrane device (3), and the water-saving device (7) is connected to the second outlet (54) and the pre-treated water tank (2) respectively. When the storage tank (5) is in the second working state, the liquid inlet return port (51) is connected to the product water side of the multi-stage reverse osmosis membrane device (3), and the first outlet (53) is connected to the chemical washing device (6).

2. The purified water preparation system according to claim 1, characterized in that, The pretreatment water tank (2) is equipped with a liquid level detector, which can detect the liquid level of the pretreatment water tank (2).

3. The purified water preparation system according to claim 1, characterized in that, The water-saving device (7) includes a water-saving reverse osmosis membrane device (72) and a filter (73). The water-saving reverse osmosis membrane device (72) has a water-saving inlet side (721), a water-saving product side (722), and a water-saving concentrate side (723). The water-saving inlet side (721) can be connected to the second liquid outlet (54). The water-saving product side (722) is connected to the pre-treated water tank (2). The filter (73) is connected to the water-saving concentrate side (723) and the water-saving inlet side (721) respectively.

4. The purified water preparation system according to claim 3, characterized in that, The water-saving device (7) also includes a tank (74) containing a scale inhibitor, which is connected to the water-saving inlet side (721).

5. The purified water preparation system according to claim 3, characterized in that, The water-saving device (7) also includes a high-pressure pump (71), which is connected to the second liquid outlet (54) and the water-saving inlet side (721).

6. The purified water preparation system according to claim 5, characterized in that, The water-saving device (7) further includes a water-saving control valve (77), which is located on the connecting pipeline between the high-pressure pump (71) and the second liquid outlet (54).

7. The purified water preparation system according to claim 1, characterized in that, The multi-stage reverse osmosis membrane device (3) includes a first-stage reverse osmosis membrane device (31) and a second-stage reverse osmosis membrane device (32) connected in sequence. The first-stage reverse osmosis membrane device (31) is connected to the pretreatment water tank (2), and the second-stage reverse osmosis membrane device (32) is connected to the electro-deionization device (4). The chemical cleaning device (6) can forward clean the first-stage reverse osmosis membrane device (31).

8. The purified water preparation system according to claim 7, characterized in that, The first-stage reverse osmosis membrane device (31) has a first-stage inlet water side (311), a first-stage product water side (312), and a first-stage concentrate side (313). The first-stage inlet water side (311) can be connected to the pre-treated water tank (2) and the first outlet (53) respectively. The first-stage product water side (312) can be connected to the second-stage reverse osmosis membrane device (32) and the inlet return water port (51). The first-stage concentrate side (313) can be connected to the inlet return water port (51).

9. The purified water preparation system according to claim 1, characterized in that, The pretreatment equipment (1) includes a sand filter (11) and an ultrafiltration device (12) connected together. The ultrafiltration device (12) can be connected to the pretreatment water tank (2). The chemical washing equipment (6) can clean the ultrafiltration device (12) in the forward direction.

10. The purified water preparation system according to claim 9, characterized in that, The washing device (6) includes a first washing branch (68) and a washing circuit (63). The storage tank (5) has a return port (52). The first washing branch (68) can be connected to the first outlet (53) and the inlet of the ultrafiltration device (12) respectively. The washing circuit (63) can be connected to the outlet of the ultrafiltration device (12) and the return port (52) respectively.

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