Water purifier and water purification method

Abstract

To provide a water purifier capable of improving an initial permeable water quality of a reverse osmosis membrane when the apparatus is restarted.SOLUTION: A water purifier 1 includes a raw water supply channel 11 that supplies raw water to a reverse osmosis membrane 21, a water purification part 2 that separates and generates permeable water and concentrated water from the raw water using the reverse osmosis membrane 21 and supplies the permeable water, a permeable water supply channel 12 that supplies permeable water from the reverse osmosis membrane 21 from a water discharge port 12a to the outside, a drainage route 13 that drains the concentrated water that could not permeate the reverse osmosis membrane 21, a pressurized permeable water tank 3 installed in the permeable water supply channel 12 to temporarily store the permeable water under pressure, a check valve B3 installed between the pressurized permeable water tank 3 and the water discharge port 12a in the permeable water supply channel 12, and an open / close part 5 that closes the raw water supply channel 11 when the pressure in the permeable water supply channel 12 reaches a predetermined pressure and opens the raw water supply channel 11 when the pressure in the permeable water supply channel 12 does not reach the predetermined pressure.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water purification device and a water purification method. [Background technology]

[0002] In recent years, research, development, and application of water treatment systems have progressed in various fields. In particular, in water treatment systems aimed at purifying water, it is important to reduce the amount of chemical compounds dissolved in water. One method for reducing these chemical compounds is to use a reverse osmosis membrane. A reverse osmosis membrane is a semipermeable membrane with ultrafine gaps between polymer membranes, and applies a high pressure greater than the osmotic pressure to a solution with high osmotic pressure, forcing water molecules to pass through the semipermeable membrane, thereby reducing dissolved substances. By using a reverse osmosis membrane, only water molecules can be selectively passed through, and dissolved substances can be reduced with high precision. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 60-882 Summary of the Invention [Problem to be solved by the invention]

[0004] However, water treatment systems using reverse osmosis membranes have a problem in that the quality of the water deteriorates between the time the supply of purified water is temporarily stopped and the time it is restarted again. This deterioration in water quality is a major issue, especially when the system is turned on and off frequently.

[0005] In other words, water purification using reverse osmosis membranes is based on the principle that water in a low-concentration solution permeates through a semipermeable membrane and flows into a high-concentration solution, maintaining a constant osmotic pressure (forward osmosis phenomenon).By deliberately applying a pressure greater than the osmotic pressure to a high-concentration solution, the water in the solution is forced to permeate the semipermeable membrane, and the membrane's separation ability separates the water into water from which most of the inorganic and organic matter has been removed (hereinafter referred to as permeated water) and water in which the inorganic and organic matter has been concentrated (hereinafter referred to as concentrated water), resulting in the permeated water (reverse osmosis phenomenon).

[0006] When the system is shut down, the pressure difference becomes small or almost nonexistent because the pressurized state is released, and reverse osmosis disappears, becoming forward osmosis, causing the water that was separated into permeated water and concentrated water by the semipermeable membrane to mix again (concentration difference diffusion phenomenon). The concentration difference diffusion phenomenon is also called RO creep, and when this phenomenon occurs, the water that once permeated the semipermeable membrane mixes with the water remaining in the permeable membrane, so when the system is restarted, the initial water quality of the permeated water discharged approaches that of the raw water. In other words, the quality of the permeated water that was supposed to be separated and supplied before the system was shut down will deteriorate in the early stages of restarting operation.

[0007] The mixing of the permeated water and the residual water in the osmosis membrane due to this phenomenon increases the mixed water volume as the size of the reverse osmosis membrane element increases, and the longer the shutdown time, the more the RO creep phenomenon progresses, contributing to the deterioration of the initial discharge water quality when restarting operation. In addition, in recent years, there is a demand for a large amount of permeated water per unit time, but if a reverse osmosis membrane with a large amount of permeated water per unit time is used, the amount of both the permeated water that permeates the reverse osmosis membrane and the concentrated water that cannot permeate and is discharged will both increase. This inevitably increases the amount of dissolved substances that are once rejected by the semipermeable membrane and then move to the permeated water side due to the forward osmosis phenomenon.

[0008] Due to this RO creep phenomenon, the rejection rate of the reverse osmosis membrane for soluble substances temporarily becomes small. If pressure is applied again to increase the permeation rate of the raw water, the solutes are blocked by the membrane surface due to the separation effect, and the rejection rate approaches the membrane's original value. However, when the equipment is first restarted, a large amount of low-quality water that does not meet the target quality will be discharged. Therefore, even for household-level equipment, careful management is required, such as creating a path to drain the initial permeated water when the equipment is restarted and carrying out additional controls, and creating a system to monitor the permeated water quality, which ultimately leads to increased costs.

[0009] An object of an embodiment of the present invention is to provide a water purification device that can improve the quality of water initially permeated through a reverse osmosis membrane when the device is restarted. [Means for solving the problem]

[0010] The water purification device of this embodiment includes a raw water supply channel that supplies raw water to a reverse osmosis membrane, a water purification section that separates and generates permeated water and concentrated water from the raw water using the reverse osmosis membrane and supplies the permeated water, a permeated water supply channel that supplies the permeated water from the reverse osmosis membrane to the outside from an outlet, a drainage path that drains concentrated water that could not permeate through the reverse osmosis membrane, a pressurized permeated water tank provided in the permeated water supply channel that temporarily stores the permeated water in a pressurized state, a check valve provided in the permeated water supply channel between the pressurized permeated water tank and the outlet, and an opening / closing section that closes the raw water supply channel when the pressure in the permeated water supply channel reaches a predetermined pressure, and opens the raw water supply channel when the pressure in the permeated water supply channel is below the predetermined pressure.

[0011] In the water purification method of this embodiment, after the supply of the permeate water from the water outlet in the permeate supply channel is stopped, the permeate water is supplied to the permeate water tank until the water pressure detected by a pressure sensor installed between the water outlet and the check valve reaches a predetermined pressure, and the permeate water that has been temporarily stored in a pressurized state in the pressurized permeate water tank is caused to flow back to the reverse osmosis membrane side and discharged from the concentrated water discharge side. Effect of the Invention

[0012] The embodiment of the present invention can improve the quality of the initial permeate water from the reverse osmosis membrane when the apparatus is restarted to a level similar to that of the apparatus when it is normally operating. [Brief description of the drawings]

[0013] [Figure 1] 1 is a system diagram showing a configuration of an embodiment of a water purification device of the present invention. [Diagram 2] 2A and 2B are cross-sectional views of the pressurized permeate tank of the embodiment of FIG. 1, showing the tank empty of permeate (A), during the supply of permeate (B), and full of permeate (C). [Diagram 3] 4 is a flowchart showing a processing procedure according to an embodiment. [Figure 4] FIG. 2 is a system diagram showing a state in which the supply of permeate water is stopped in the embodiment of FIG. 1. [Diagram 5] FIG. 2 is a system diagram showing the RO creep water drainage state of the embodiment of FIG. 1. [Figure 6] FIG. 11 is a system diagram showing a configuration of a modified example of the position of the auto shutoff valve in the water purification device of the embodiment. [Figure 7] FIG. 7 is a system diagram showing a state in which the supply of permeate water is stopped in the embodiment of FIG. 6. [Figure 8] FIG. 7 is a system diagram showing the RO creep water drainage state of the embodiment of FIG. 6. [Figure 9] FIG. 11 is a system diagram showing the configuration of a modified example in which the auto shutoff valve in the water purification device of the embodiment is replaced with an electromagnetic valve for opening and closing. [Figure 10] FIG. 10 is a system diagram showing a state in which the supply of permeate is stopped in the embodiment of FIG. 9. [Figure 11] FIG. 10 is a system diagram showing the RO creep water drainage state of the embodiment of FIG. 9. [Figure 12] 4 is a cross-sectional view showing an example of an adjustment unit that adjusts the pressure of the pressurizing unit. FIG. [Figure 13] FIG. 13 is a system diagram showing an example in which a recovery path is provided. [Figure 14] FIG. 13 is a system diagram showing an example in which a storage tank is provided instead of a pressurized permeate tank. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A mode for carrying out the present invention (hereinafter, referred to as an embodiment) will be specifically described with reference to the drawings. In this embodiment, a water treatment system using a reverse osmosis membrane is applied to a home water purification device.

[0015] [composition] As shown in the system diagram of FIG. 1, the water purification device 1 of this embodiment includes a water purification section 2 using a reverse osmosis membrane 21.

[0016] (Water Purification Department) The water purification unit 2 separates raw water (tap water in this embodiment) into permeated water and concentrated water using a reverse osmosis membrane 21, and supplies the permeated water. The reverse osmosis membrane 21 is a membrane element built into a vessel, which is a container. The membrane element reduces heavy metals, chemicals, dissolved substances, etc., using the principle of reverse osmosis described above.

[0017] The water purification unit 2 is connected to a raw water supply channel 11, a permeated water supply channel 12, and a drainage path 13. The raw water supply channel 11 is a raw water supply channel that supplies raw water to the reverse osmosis membrane 21 of the water purification unit 2. The raw water supply channel 11 is connected to the raw water supply side of the reverse osmosis membrane 21. The permeated water supply channel 12 is a channel that supplies permeated water from the reverse osmosis membrane 21 of the water purification unit 2 to the outside from the water outlet 12a. The permeated water supply channel 12 is connected to the permeated water supply side of the reverse osmosis membrane 21. The water outlet 12a is a faucet of the faucet 4 described later. The drainage path 13 is a path that drains concentrated water that could not permeate the reverse osmosis membrane 21 of the water purification unit 2. The drainage path 13 is connected to the concentrated water drainage side of the reverse osmosis membrane 21.

[0018] (Raw water supply route) The raw water supply line 11 is provided with a ball valve B1, a check valve B2, a sediment filter SF, an activated carbon filter CF, and a pump P. The ball valve B1 opens and closes to switch between supplying raw water and not supplying it. The check valve B2 is a valve that prevents the backflow of raw water. The sediment filter SF is a fiber filter that removes impurities of about 5 microns or more, such as rust, sand, and dust. The activated carbon filter CF is a filter that protects the reverse osmosis membrane 21 made of a polyamide material by removing residual chlorine and the like. The pump P is a pressure pump that increases the pressure on the raw water side of the reverse osmosis membrane 21.

[0019] (Permeated water supply path) The permeate supply passage 12 is provided with a pressurized permeate tank 3, a check valve B3, a pressure sensor PI, a pressure switch SW, a post filter PF, and a water faucet 4.

[0020] <Pressurized permeate tank> The pressurized permeated water tank 3 temporarily stores the permeated water in a pressurized state. As shown in FIG. 2, the pressurized permeated water tank 3 has a container 31, a diaphragm 32, a water storage section 33, and a pressurizing section 34. The container 31 is cylindrical and has a dome shape with the top and bottom bulging outward, and is capable of storing purified water in the internal space. The container 31 is provided with a water supply and drainage port 31a. The water supply and drainage port 31a is connected to the permeated water supply channel 12.

[0021] The diaphragm 32 is a member that airtightly divides the inside of the container 31 into two regions. The diaphragm 32 is made of an elastic body. For example, the periphery of a butyl rubber sheet is airtightly attached to the inner surface of the container 31.

[0022] 2(B) and (C), the water storage section 33 is an area in which the permeated water is stored. The water storage section 33 is provided so that the internal pressure can be varied according to the amount of stored water. That is, the internal pressure of the water storage section 33 increases as the amount of stored water increases, and decreases as the amount of stored water decreases. The water storage section 33 is one of the areas in the container 31 separated by the diaphragm 32, and is connected to the water supply and drainage port 31a. In the figures, the shaded area represents the permeated water.

[0023] Pressurizing section 34 is a region that applies pressure to water storage section 33. Pressurizing section 34 is the other region in container 31 separated by diaphragm 32, and applies pressure to water storage section 33 by the internal gas (air in this embodiment) as shown in FIG. 2(A). When no water is stored, diaphragm 32 is in contact with the inside of container 31 due to the pressure of pressurizing section 34, and the volume of water storage section 33 is almost zero. Then, as shown in FIG. 2(B) and FIG. 2(C), as the amount of stored purified water supplied from water supply and drainage port 31a increases, diaphragm 32 expands, and the internal pressure of water storage section 33 and pressurizing section 34 increases.

[0024] In this type of pressurized permeated water tank 3, the amount of water stored in the water storage section 33 can be adjusted by expanding and contracting the diaphragm 32 according to the capacity of the reverse osmosis membrane 21 and the amount of water that generates RO creep. Also, as described above, the internal pressure of the water storage section 33 is variable by the air pressure of the pressurizing section 34 according to the amount and pressure of water to be reversed.

[0025] <Check valve> The check valve B3 is a valve that prevents the backflow of the permeated water. The check valve B3 is provided between the pressurized permeated water tank 3 and the water outlet 12a, and prevents the backflow of the permeated water that has flowed after the pressurized permeated water tank 3.

[0026] <Pressure sensor> The pressure sensor PI detects the pressure of the purified water in the permeate supply channel 12 .

[0027] <Pressure switch> The pressure switch SW turns the pump P on and off according to the pressure detected by the pressure sensor PI.

[0028] <Post filter> The post filter PF is equipped with activated carbon to remove odors that may be transferred from the elastic material to the permeate that has passed through the reverse osmosis membrane 21 in the primary storage tank, and a UF sterilization filter to enhance microbial safety. Note that ceramics may be used instead of activated carbon, and a UV germicidal lamp may be used instead of the UF sterilization filter to sterilize the water. In addition, when using purified water for experiments, an ion exchange resin called a mixed bed, which is a mixture of anion and cation resins, may be used.

[0029] <Faucet> The faucet 4 is a faucet that receives water from a tap when operated by a user. The faucet 4 can open and close the purified water path by operating means such as a lever or a handle. This operating means is provided at or near a faucet in a home kitchen, washroom, etc. The faucet constitutes the purified water outlet 12a as described above. In other words, the faucet 4 opens and closes the outlet 12a, and switches between starting and stopping the supply of permeated water from the outlet 12a.

[0030] (Drainage route) The drainage path 13 is provided with a flow rate adjustment valve B4 and a check valve B5. The flow rate adjustment valve B4 is always open, and discharges concentrated wastewater and the like from the concentrated side of the membrane element. The flow rate adjustment valve B4 is also called a restrictor, and raw water whose flow rate is restricted by the flow rate adjustment valve B4 flows in a direction that permeates the reverse osmosis membrane 21. The check valve B5 is provided after the flow rate adjustment valve B4, and prevents backflow from the wastewater discharge port of the drainage path 13.

[0031] (Opening and closing part) Furthermore, the water purification device 1 has an opening / closing unit 5. The opening / closing unit 5 closes the raw water supply channel 11 when the pressure in the permeate water supply channel 12 reaches a predetermined pressure, and opens the raw water supply channel 11 when the pressure in the permeate water supply channel 12 does not reach the predetermined pressure. The opening / closing unit 5 in this embodiment is an auto shutoff valve 51.

[0032] The auto shutoff valve 51 has a pair of paths 51a and 51b, and opens and closes the other path 51a when the pressure of the other path 51b increases. The predetermined pressure of the path 51b for closing the path 51a is determined by the pressure difference between the paths 51a and 51b, and is not necessarily determined to a specific value, but is an approximately constant pressure under normal use conditions. In the auto shutoff valve 51 of this embodiment, the path 51a of the pair of paths 51a and 51b is a flow path through which the raw water supply path 11 passes, and the other path 51b is a flow path through which the permeate supply path 12 passes. The path 51a is provided between the pump P and the water purification unit 2, and the path 51b is provided between the check valve B3 and the water outlet 12a (between the check valve B3 and the pressure sensor PI in this embodiment). Path 51a is one-way, from the raw water side toward reverse osmosis membrane 21, while path 51b flows in both directions. When pressurized, an expansion valve in path 51b expands, blocking path 51a.

[0033] [Effect] Next, the operation of this embodiment configured as described above will be described with reference to the flow chart in FIG. 3 and the system diagrams in FIG. 4 and FIG.

[0034] (water supply) The operation of the user receiving water supply from the reverse osmosis membrane 21 will be described. The operation means of the water faucet 4 is in a water stop state, and the auto shutoff valve 51 that opens and closes the flow path of raw water and permeated water is also in a closed state. In this state, the user operates the operation means to open the water faucet 4 (step S01). Then, the internal pressure of the permeated water supply path 12 from the check valve B3 to the water outlet 12a drops below a certain pressure (step S02), so that the expansion of the inner membrane of the path 51b of the auto shutoff valve 51 is released and the path 51a opens (step S03). When the pressure sensor PI detects that the pressure of the permeated water supply path 12 has dropped below a predetermined pressure (step S04), the pressure switch SW operates the pump P (step S05). As a result, the raw water that has flowed into the raw water supply path 11 passes through the sediment filter SF and the activated carbon filter CF, whereby impurities are removed and chlorine and the like are rendered harmless.

[0035] Furthermore, the raw water is subjected to additional pressure by the pump P in addition to the raw water pressure, and is separated into permeated water in which heavy metals, chemicals, dissolved substances, etc. have been reduced, and concentrated water by passing through the reverse osmosis membrane 21 (step S06). The permeated water flows through the permeated water supply passage 12 toward the faucet 4, where odors, etc. are removed by the post filter PF and microbial safety is increased by the UF sterilization filter, etc., before being discharged from the faucet 4 supplied from the water outlet 12a (step S07). The concentrated water is discharged through the drainage path 13. The recovery rate can be adjusted by the flow rate adjustment valve B4. The recovery rate is the production ratio between the amount of permeated water through the reverse osmosis membrane 21 itself and the amount of raw water supplied, which is determined by the reverse osmosis membrane 21 and the flow rate adjustment valve B4 that controls the amount of concentrated drainage.

[0036] (water stop) Next, a case where the user stops the supply of purified water by the reverse osmosis membrane 21 will be described. That is, the user operates the operating means to close the water tap 4 (step S08). Meanwhile, raw water continues to be supplied, so the permeated water starts to flow (storage) into the pressurized permeated water tank 3 (step S09). When the pressures of the water storage section 33 and the pressurizing section 34 of the pressurized permeated water tank 3 are balanced (YES in step S10), the flow of the permeated water into the pressurized permeated water tank 3 stops (step S11). As shown in FIG. 4, the internal pressure of the permeated water supply passage 12 (the portion of the permeated water supply passage 12 indicated by the thick line in the figure) increases (step S12), and when the pressure sensor PI detects that the water pressure has reached a predetermined level (YES in step S13), the pressure switch SW stops the pump P (step S14).

[0037] Then, when the pressure between the passage 51b of the auto shutoff valve 51 and the faucet 4 reaches a certain pressure, the inner membrane of the passage 51b of the auto shutoff valve 51 is pushed down, and the passage 51a is closed (step S15), thereby cutting off the supply of raw water (step S16). When the faucet 4 is closed in this way, the inflow of raw water is finally blocked after a delay. The inflow of raw water is limited to the portion indicated by the thick line in the figure of the raw water supply passage 11. In addition, in the permeated water supply passage 12, a pressurized state is maintained between the check valve B3 installed after the pressurized permeated water tank 3 and the faucet 4.

[0038] 5, the temporarily stored permeated water flows back from the pressurized permeated water tank 3, which is installed between the outlet side of the reverse osmosis membrane 21 and the water faucet 4 and maintains a constant pressure, to the outlet side of the reverse osmosis membrane 21. The backflowing permeated water passes through the reverse osmosis membrane 21 and is drained from the concentrated side of the membrane element, which is open to the atmosphere, through the drainage path 13 (step S17).

[0039] As a result, with check valve B3 at the very end, almost all of the stored water in pressurized permeated water tank 3, the permeated water that has already passed through reverse osmosis membrane 21 in water purification section 2, temporarily retained untreated water, the water not affected by pressure before reverse osmosis membrane 21, and the water in each of the pipes and joints are drained from the concentrated water drain side. In this embodiment, an air pressure of 1 atmosphere or more is applied by pressurizing section 34, and the permeated water stored in water storage section 33 is drained all at once.

[0040] This phenomenon in which the permeate water that has once passed through the reverse osmosis membrane 21 returns to eliminate RO creep and is discharged from the concentrated wastewater side is called reflux water as a new concept and can be distinguished from simple backflow. Moreover, this phenomenon differs from the suck-back phenomenon seen in conventional seawater desalination, and intentionally utilizes the swing back of the permeate water (called permeate swing), and is a method for eliminating the RO creep phenomenon that occurs within the reverse osmosis membrane 21. Moreover, since the remaining concentrated water is also discharged, it differs from simple mixing of the permeate water with the concentrated water due to the return of the permeate water.

[0041] When the user wants to obtain purified water again, as in the case of the water supply described above, when the water tap 4 is opened, the pressure in the permeate supply channel 12 drops, which is detected by the pressure sensor PI, and at the same time, the inner membrane of the channel 51a, which had been closed by the channel 51b of the auto shutoff valve 51, returns to its original position, opening the raw water supply channel 11 and starting the supply of raw water. Subsequent operations are the same as those from step S02 onwards. When the system is restarted, the water that causes RO creep (RO creep water) has been discharged, so that the initial permeate water quality is improved to the same level as that in the normal operating state of the device, and the water is discharged.

[0042] [effect] (1) The water purification device 1 of this embodiment includes a raw water supply channel 11 that supplies raw water to the reverse osmosis membrane 21, a water purification section 2 that separates and generates permeated water and concentrated water from the raw water using the reverse osmosis membrane 21 and supplies the permeated water, a permeated water supply channel 12 that supplies the permeated water from the reverse osmosis membrane 21 to the outside from an outlet 12a, a drainage path 13 that drains concentrated water that could not permeate through the reverse osmosis membrane 21, a pressurized permeated water tank 3 provided in the permeated water supply channel 12 and temporarily stores the permeated water in a pressurized state, a check valve B3 provided in the permeated water supply channel 12 between the pressurized permeated water tank 3 and the outlet 12a, and an opening / closing section 5 that closes the raw water supply channel 11 when the pressure in the permeated water supply channel 12 reaches a predetermined pressure and opens the raw water supply channel 11 when the pressure in the permeated water supply channel 12 does not meet the predetermined pressure.

[0043] In the water purification method of the water purification device 1 of this embodiment, after the supply of permeated water from the water outlet 12a in the permeated water supply channel 12 is stopped, the permeated water is supplied to the pressurized permeated water tank 3 until the water pressure detected by the pressure sensor PI reaches a predetermined pressure, and the permeated water temporarily stored in the pressurized permeated water tank 3 in a pressurized state is caused to flow back to the reverse osmosis membrane 21 side and discharged from the concentrated water discharge side. Furthermore, after the supply of permeated water from the permeated water supply channel 12 is stopped, the opening / closing unit 5 closes the raw water supply channel 11 when the pressure in the permeated water supply channel 12 reaches a predetermined pressure.

[0044] In this way, when the operation and water supply of the water purification device 1 is stopped, the water in the pressurized permeated water tank 3 in which the permeated water is temporarily stored under pressurized conditions flows back in through the permeated water outlet side of the reverse osmosis membrane 21 and is discharged from the concentrated side of the reverse osmosis membrane 21 which is open to the atmosphere, so that the concentrated water that has been retained inside the membrane element of the reverse osmosis membrane 21 is replaced with the permeated water and does not remain. In other words, when the water purification device 1 is restarted, the effects of low-quality water, i.e., non-permeated water, can be eliminated, and stable high-quality water can be supplied from the start of the restart, so that the water quality can be improved to the same level as during normal operation and the problem of RO creep can be solved.

[0045] Generally, there are two types of home water purifiers using reverse osmosis membranes: storage tank type and direct type without storage tank. The storage tank type compensates for the lack of permeate volume by using a storage tank. However, the permeate that permeated the reverse osmosis membrane and was stored in the storage tank was supplied from the outlet all at once when the supply started, which caused the problem of RO creep mentioned above. However, since the stored permeate mixed with the water that was undergoing the creep phenomenon, the deterioration of water quality was not recognized as RO creep on the surface. In addition, a large storage tank was required to ensure the supply of permeate, which increased the required installation space. Furthermore, since the permeate was kept under pressure over a wide area inside the device, there was a possibility of leakage, and if leakage occurred, it could not be stopped.

[0046] The direct type supplies permeated water directly by greatly increasing the area of ​​the reverse osmosis membrane. The advantages are that some have a mechanism that allows the raw water supply to be stopped at the faucet, the structure stops the inflow of the raw water to the device at the inlet side, so water leakage accidents are unlikely to occur, the overall size is significantly smaller because a water storage tank is not used, there is no risk of impurities leaching from the water storage tank or water pollution, and the required amount of water can be supplied directly, which greatly reduces the stress of the user. However, even with the direct type, the problem of RO creep occurs when the device is restarted after being stopped, and the increase in the volume of the reverse osmosis membrane means that the amount of water causing RO creep is also increasing, so this was the most important unsolved issue for reverse osmosis membrane water purification devices in the near future when water purification using reverse osmosis membranes will be required.

[0047] In most conventional tank systems, a small reverse osmosis membrane with a small amount of permeated water is used, and a tank is provided for the purpose of "storing" the purified water to be discharged. The pressurized permeated water tank 3 of this embodiment is not a "permeated water storage" but a temporary "storage state" and a temporary "pressure storage state", and is significantly different from conventional tank systems in that it is a structure for the purpose of "discharging water that causes RO creep" in the reverse osmosis membrane 21. In addition, a structure in which the permeated water that has been stored for a while flows back from the permeated water outlet side of the reverse osmosis membrane 21 has not been used in the past, and is a groundbreaking idea. Since the water is not stored for the purpose of being used as permeated water, the pressurized permeated water tank 3 does not need to be maintained in a "storage state" after the device is stopped, and after the device is stopped, the water in the pressurized permeated water tank 3 is used to "discharge water that causes RO creep" in the reverse osmosis membrane 21, so from then on, the permeated water supply passage 12 from the check valve B2 to the front side, including the pressurized permeated water tank 3, becomes empty.

[0048] That is, a pressurized permeated water tank 3 is provided to temporarily store the permeated water under pressure, and the permeated water can be reversed from the pressurized permeated water tank 3 when operation is stopped or water discharge is stopped. This allows the water that is the source of concentration diffusion that causes RO creep and that is retained in the reverse osmosis membrane 21 to be replaced with the permeated water, so that when operation is restarted, the newly permeated water can be discharged from the beginning. The water within the membrane element volume of the reverse osmosis membrane 21 has almost the same quality as the permeated water immediately after restarting operation, ensuring high water quality. The RO creep phenomenon itself is eliminated by removing untreated water from within the reverse osmosis membrane 21, which causes RO creep.

[0049] In this way, all of the temporarily stored permeate water is used to eliminate RO creep, and none of it is discharged from the drinking water side. The temporary storage state lasts only a few seconds after the system is shut down, which is different from the concept of storage in a conventional water tank. This overcomes the weaknesses of the conventional water storage tank method and direct method, and makes it possible to supply safe and secure water from the very start of the system's restart.

[0050] Furthermore, when the device is stopped, the raw water is stopped by the opening / closing unit 5. Therefore, only a small amount of water in the short permeate water supply path 12 from the check valve B3 to the water outlet 12a and a small amount of water in the raw water supply path 11 from the ball valve B1 to the opening / closing unit 5 are pressurized, so the number of parts that may affect water leakage from the device is minimized, and the risk of water leakage is extremely low.

[0051] In other words, in the conventional tank system, most of the system from the raw water supply source to the water outlet was always pressurized when the system was stopped, which meant that there was a risk of leakage when parts had a problem. In this embodiment, the permeated water present in the pressurized permeated water tank 3 and the check valve B2 installed thereafter is discharged to the concentrated side, so there are no pressurized parts between the pressurized permeated water tank 3 and the water outlet 12a, resulting in a structure with a low risk of leakage. Even if the internal pressurized state continues and a leakage accident occurs, the risk of leakage amount and duration can be kept incomparably low.

[0052] Furthermore, the pressurized permeate tank 3 is not installed for the purpose of covering the permeate production capacity of a small reverse osmosis membrane as in the past, but only needs to store enough water to drain the untreated water that causes RO creep, so the entire device can be made extremely compact.

[0053] More specifically, due to the structure of the membrane element, the amount of water that exists as permeate in the reverse osmosis membrane 21 and may be affected by RO creep is approximately 40% of the total volume of the membrane element. If the volume of untreated water is made to flow down from the concentrated water side using permeate as much as possible relative to the total volume of the membrane element, RO creep itself will be eliminated.

[0054] The mainstream small direct type membrane element for home reverse osmosis membranes 21 is called the 3012 type, which is 3 inches in diameter and 12 inches in length and has a total volume of about 1,300 ml, so the tank storage capacity to eliminate RO creep is 40% of 1300 ml = about 420 ml. The pressurized permeate tank 3 is not intended to store as much permeate water as possible like conventional storage tanks, so it only needs to have the volume necessary to eliminate RO creep.

[0055] Therefore, the pressurized water storage tank does not need to be as large as a conventional water storage tank with a capacity of 3 gallons (approximately 12 L), and a tank that can store and pressurize approximately 0.5 L will suffice this time. In other words, for example, the volume of the pressurized permeated water tank 3 (water storage section 33) only needs to be approximately 40 to 50% of the volume of the reverse osmosis membrane 21, even taking into account the margin of error. This leads to a more compact device.

[0056] (2) The pressurized permeated water tank 3 temporarily stores the permeated water and has a water storage section 33 in which the internal pressure can be varied according to the amount of stored water. Therefore, as the amount of stored water increases, the internal pressure increases and a discharge pressure can be obtained. In other words, the amount of stored water in the pressurized permeated water tank 3 can be flexibly changed according to the amount of untreated water (water that causes RO creep) in the reverse osmosis membrane 21.

[0057] (3) The pressurized permeated water tank 3 has a pressurizing section 34 that applies pressure to the water storage section 33 by gas. Therefore, since pressurization can be achieved by gas pressure, a special drive mechanism or the like is not required, and the pressurized permeated water tank 3 can be configured to be simple, inexpensive, and small.

[0058] (4) The pressurized permeated water tank 3 is divided into a water storage section 33 and a pressurized water tank 34 by a diaphragm 32 made of an elastic material. Therefore, the pressure on the water storage section 33 can be adjusted by expanding and contracting the elastic material, so that a simpler, less expensive, and smaller pressurized permeated water tank 3 can be constructed.

[0059] (5) The opening / closing unit 5 is an auto shutoff valve 51 in which one path 51a of a pair of paths 51a, 51b is a flow path through which the raw water supply path 11 passes and the other path 51b is a flow path through which the permeate water supply path 12 passes. Therefore, a sensor or the like for opening and closing the raw water supply path 11 is not required, and the raw water supply path 11 can be closed in response to a pressure increase in the permeate water supply path 12.

[0060] (6) A pump P is provided in the raw water supply passage 11 to increase the pressure on the raw water side, a pressure sensor PI is provided between the water outlet 12a and the check valve B3, and a pressure switch SW which stops the pump P when the pressure detected by the pressure sensor PI reaches a predetermined pressure when the water outlet 12a is closed, and operates the pump P when the pressure detected by the pressure sensor PI falls below the predetermined pressure when the water outlet 12a is opened. Therefore, the operation of the pump P can be stopped with a delay from when the water outlet 12a is closed, and operated with a delay from when the water outlet 12a is opened.

[0061] [Variations] (1) This embodiment is not limited to the above-mentioned embodiment. For example, as shown in Figs. 6 to 8, the length of the piping of the permeate supply channel 12 from the water purification unit 2 to the opening / closing unit 5 (auto shutoff valve 51) may be increased by disposing a post filter PF between the water purification unit 2 and the check valve B3. This allows the amount of reflux water to be increased as shown by the shaded path in Fig. 8. In addition, the raw water supply channel 11 upstream of the opening / closing unit 5 may be shortened by disposing a sediment filter SF and an activated carbon filter CF between the water purification unit 2 and the opening / closing unit 5 (auto shutoff valve 51). This allows the section in which the permeate supply channel 12 and the raw water supply channel 11 are pressurized when the device is stopped to be shortened as shown by the thick line path in Fig. 7, thereby reducing the risk of water leakage.

[0062] (2) The opening / closing unit 5 is not limited to the auto shutoff valve 51. As shown in Figs. 9 to 11, the opening / closing unit 5 may be an opening / closing valve 52 provided in the raw water supply passage 11. The opening / closing valve 52 is provided in the raw water supply passage 11, and closes the raw water supply passage 11 when the pressure detected by the pressure sensor PI reaches a predetermined pressure when the water outlet 12a is closed, and opens the raw water supply passage 11 when the pressure detected by the pressure sensor PI falls below the predetermined pressure when the water outlet 12a is opened. A solenoid valve is used as the opening / closing valve 52.

[0063] Although the stop of operation of the pump P is controlled by detection by the pressure sensor PI, it may become necessary to fine-tune the stop time depending on the type of pump P, the structure of the pressurized permeated water tank 3, etc. In such a case, a delay timer can be provided that receives a signal from the pressure sensor PI and adjusts the stop time of the pump P. This delay timer allows fine adjustment of the temporary stored water volume and stored pressure in the pressurized permeated water tank 3 by delaying the stop time of the pump P by, for example, several seconds or less than one second, rather than immediately stopping the pump P when detected by the pressure sensor PI.

[0064] In this way, when the on-off valve 52 is used instead of the auto shutoff valve 51, the check valve B3 installed immediately after the pressurized permeate tank 3 is installed immediately before the pressure switch SW in order to ensure the amount of untreated water to be discharged, which works more effectively in discharging the amount of water that causes RO creep. In this case, too, it is preferable to increase the amount of reflux water, as shown by the shaded path in Figure 11. Also, as shown by the thick line path in Figure 10, it is preferable to shorten the section in which the permeate supply channel 12 and raw water supply channel 11 are pressurized when the apparatus is stopped, to reduce the risk of water leakage.

[0065] (3) The capacity of the pressurized permeated water tank 3 can be determined by measuring the amount of water that causes RO creep through experiments to accommodate various sizes of reverse osmosis membrane 21, and a capacity that eliminates the RO creep phenomenon can be selected. In addition, if the pressure of the pressurizing unit 34 of the pressurized permeated water tank 3 is set low, the amount of water stored therein increases, and a certain amount of permeated water can always be left behind. In this case, for example, the pressure can be made equal to atmospheric pressure only after a certain amount of permeated water has flowed in, but the pressurized permeated water tank 3 can be made smaller. In other words, even if the container 31 is made smaller, the volume of the pressurized permeated water tank 3 that is temporarily stored and stored can be maximized by lowering the internal pressure of the pressurized permeated water tank 3 to the minimum level at which the stored water is quickly recirculated.

[0066] (4) In the above embodiment, the diaphragm 32 is made of butyl rubber, but may be made of other elastic and stretchable materials. Furthermore, the diaphragm 32 may be provided in the pressurized permeated water tank 3 so as to be movable by a variable mechanism, thereby increasing or decreasing the volume of the pressurizing unit 34 and making the pressure adjustable. Also, an adjustment unit for adjusting the pressure of the pressurizing unit 34 may be provided. For example, as shown in FIG. 12(A), the adjustment unit 35 may be formed of a membrane 35a and an adjustment tool 35b. The membrane 35a is an elastic and stretchable member, and seals the bottom of the pressurizing unit 34. The membrane 35a may be formed of the same material as the membrane 32. For example, a part of the outer casing of the pressurizing unit 34 of the pressurized permeated water tank 3 is made of the membrane 35a made of an elastic material having a hardness equal to or greater than that of the membrane 32.

[0067] Adjuster 35b is a member that expands and contracts membrane 35a, and is provided at the bottom of container 31. Adjuster 35b has contact portion 35c, shaft portion 35d, and knob portion 35e. Contact portion 35c is a member that comes into contact with membrane 35a inside container 31. Shaft portion 35d is a member having contact portion 35c at one end, is threaded on its outer periphery, and is screwed into a threaded hole at the bottom of container 31 so as to penetrate therethrough. Knob portion 35e is a plate body provided at the other end of shaft portion 35d that is exposed to the outside of container 31.

[0068] When the knob 35e is rotated, the contact portion 35c can be advanced and retracted by the screw, so that when the contact portion 35c biases and expands the membrane 35a as shown in Fig. 12(B), the volume of the pressurizing portion 34 decreases, and the pressure can be increased. In the pressurized permeated water tank 3, the amount of permeated water temporarily stored and the internal pressure when the water is stored can be varied depending on the set pressure of the pressurizing portion 34 in the sealed state, but by providing a variable mechanism for changing the position of the diaphragm 32 or an adjustment mechanism (adjustment tool 35b) for expanding the membrane 35a, the volume of the pressurizing portion 34 can be varied, and the pressure can be varied. The gas used for pressurization is not limited to air, and other gases such as nitrogen may be filled.

[0069] (5) The setting of a specified or constant pressure (including water pressure) is also free, and whether a specified or constant pressure has been reached may be judged as being above that pressure, or as being greater than or exceeding that pressure, and it is equivalent to judging a pressure below the specified pressure as being less than or below the specified pressure.

[0070] (6) The pump P may be omitted, and water may be passed through the device using only the pressure of a general water supply. Any of the activated carbon filter CF, the sediment filter SF, and the post filter PF may be omitted, or all of these filters may be omitted, resulting in a water purification device 1 having only the reverse osmosis membrane 21.

[0071] (7) The operating means for opening and closing the water outlet 12a is generally a lever or a handle, but other structures may be used. For example, an opening and closing means that opens and closes in response to the operation of a button switch or object detection by a sensor, such as a solenoid valve or an electric valve, may be used.

[0072] (8) The flow rate regulating valve B4 may be provided so as to be able to adjust the discharged flow rate as appropriate depending on the type of reverse osmosis membrane 21. The flow rate regulating valve B4 may be provided with a function for manually adjusting the flow rate in a stepless manner (for example, by using a screw). A flow meter may be provided in the permeated water supply passage 12 so that the flow rate regulating valve B4 can adjust the discharged flow rate in a stepless manner depending on the ratio to the amount of permeated water measured by the flow meter.

[0073] (9) A recovery path may be provided in the drainage path 13. After entering the water purification unit 2, the raw water permeates the reverse osmosis membrane 21 to become permeated water, and then flows out as drainage to the drainage path 13 side where there is less pressure loss. Since the drainage path 13 has a flow rate regulating valve B4, the flow rate other than the constant flow rate is regulated and flows to the permeation side of the reverse osmosis membrane 21 to become permeated water. However, if the amount of water entering the reverse osmosis membrane 21 is even greater, or if the membrane area of ​​the reverse osmosis membrane 21 is small, there is a possibility that the amount of water heading to the reverse osmosis membrane 21 will be excessive. Therefore, a recovery path may be provided in order to utilize this excessive amount of water.

[0074] For example, as shown in FIG. 13, a recovery path 14 is provided that branches off from the drainage path 13 and is connected upstream of the pump P. A flow rate control valve B6 is also provided in this recovery path 14. The flow rate control valves B4 and B6 are adjusted so that the flow rate of the recovery path 14 is lower than that of the drainage path 13, so that the drainage is preferentially circulated to the drainage path 13. In addition, the water pressure on the recovery path 14 is set higher than the water pressure on the reverse osmosis membrane 21 so that the amount of permeated water from the reverse osmosis membrane 21 is set as set. If any excess water is generated, it flows through the recovery path 14 and merges upstream of the pump P, making it possible to reuse it.

[0075] (10) Instead of the pressurized permeated water tank 3, a storage tank 6 may be provided that temporarily stores the permeated water and drains it by gravity, as shown in Fig. 14. This storage tank 6 has a water supply and drainage port 62 provided at the bottom of a container 61, which is the main body, and this water supply and drainage port 62 is connected to a permeated water supply channel 12. With this, when the water tap 4 is closed, the permeated water flows into the storage tank 6, creating a temporary pressurized state, but when the inflow of raw water is closed, gravity acts to cause the permeated water in the storage tank 6 to flow downward, and the pressurized state is instantly released. In other words, the permeated water in the storage tank 6 falls by gravity, passes through the reverse osmosis membrane 21, and is drained, providing the same effect as the above embodiment.

[0076] (11) The capacity and structure of the reverse osmosis membrane 21 used in the water purification unit 2 are not limited to a specific one. In addition, as the water purification unit 2, for example, any of the reverse osmosis membrane water purifiers listed in "4 types, Table 1" of JIS-S3242, which is the standard for domestic reverse osmosis membrane water purifiers, can be used, and as the water purification device 1, for example, any of the examples shown in Figure 1 - Example of a reverse osmosis membrane water purifier (block diagram) of the same standard can be applied. In other words, the present invention does not exclude application to a specific reverse osmosis membrane water purifier and a water purification device using the same.

[0077] [Other embodiments] Although the embodiment of the present invention and the modified examples of each part have been described above, these embodiments and the modified examples of each part are presented as examples and are not intended to limit the scope of the invention. These novel embodiments described above can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims. [Explanation of symbols]

[0078] 1. Water purification equipment 2. Water Purification Section 3 Pressurized permeate tank 4 Faucet 5 Opening and closing section 11 Raw water supply route 12 Permeated water supply line 12a Outlet 13 Drainage route 14 Recovery Route 21 Reverse osmosis membrane 31 Container 31a Water supply and drainage outlet 32 Diaphragm 33 Water storage section 34 Pressurizing section 35 Adjustment section 35a membrane 35b Adjuster 35c contact part 35d shaft 35e Knob 51 Auto shutoff valve Routes 51a and 51b 52 On-off valve 6. Storage Tank 61 Container 62 Water supply and drainage outlet B1 Ball Val B2 Check valve B3 Check valve B4 Flow control valve B5 Check valve B6 Flow control valve CF Activated Charcoal Filter P-Pump PF Post Carbon Filter PI Pressure Sensor SF Sediment Filter SW Pressure switch

Claims

1. a raw water supply channel for supplying raw water to the reverse osmosis membrane; A water purification unit that separates and generates permeated water and concentrated water from raw water by the reverse osmosis membrane and supplies the permeated water; A permeate supply channel that supplies the permeate from the reverse osmosis membrane to the outside through a water outlet; a drainage path for draining the concentrated water that could not permeate the reverse osmosis membrane; a pressurized permeate tank provided in the permeate supply channel and configured to temporarily store the permeate in a pressurized state; A check valve provided in the permeate supply channel between the pressurized permeate tank and the water outlet; an opening / closing unit that closes the raw water supply channel when the pressure in the permeated water supply channel reaches a predetermined pressure, and opens the raw water supply channel when the pressure in the permeated water supply channel does not reach the predetermined pressure; A water purification device comprising:

2. 2. The water purification device according to claim 1, wherein the pressurized permeated water tank has a water storage section for temporarily storing the permeated water and an internal pressure of the tank is variable depending on the amount of stored water.

3. 3. The water purification device according to claim 2, wherein the pressurized permeate tank has a pressurizing section that applies pressure to the water storage section by gas.

4. 4. The water purification device according to claim 3, wherein the pressurized permeate tank is divided into the water storage section and the pressurizing section by a diaphragm made of an elastic material.

5. 5. The water purifying device according to claim 3, further comprising an adjustment section for adjusting the pressure of the pressurizing section.

6. 6. The water purification device according to claim 5, wherein the adjusting section is provided so as to vary the volume of the pressurizing section by a membrane made of an elastic body.

7. The water purification device according to claim 1, characterized in that the opening and closing part is an auto shut-off valve of a pair of paths, one of which is a flow path through which the raw water supply path passes and the other of which is a flow path through which the permeate supply path passes.

8. A pressure sensor is provided between the water outlet and the check valve, The water purification device according to claim 1, characterized in that the opening / closing unit is an opening / closing valve provided in the raw water supply passage and which closes the raw water supply passage when the pressure detected by the pressure sensor reaches a predetermined pressure when the water outlet is closed, and opens the raw water supply passage when the pressure detected by the pressure sensor falls below the predetermined pressure when the water outlet is opened.

9. A pump provided in the raw water supply line to increase the pressure on the raw water side; A pressure sensor provided between the water outlet and the check valve; a pressure switch which stops the pump when it is detected that the pressure detected by the pressure sensor reaches a predetermined pressure when the water outlet is closed, and which operates the pump when it is detected that the pressure detected by the pressure sensor falls below the predetermined pressure when the water outlet is opened; 2. The water purification device according to claim 1, further comprising:

10. 2. The water purification apparatus according to claim 1, wherein a storage tank is provided in place of the pressurized permeated water tank, for temporarily storing the permeated water and discharging it by gravity.

11. A water purification method for the water purification device according to claim 1, a pressure sensor provided between the outlet and the check valve, the pressure sensor detects the pressure of the permeate and detects whether the pressure of the permeate reaches a predetermined pressure, and the pressure sensor detects whether the pressure of the permeate reaches a predetermined pressure.

12. The water purification method according to claim 11, characterized in that after the supply of the permeated water from the permeated water supply channel is stopped, the opening and closing part closes the raw water supply channel when the pressure in the permeated water supply channel reaches a predetermined pressure.

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