Device for simultaneously stabilizing nano-bubble pure water and micro-bubble concentrated brine

Abstract

The application relates to a device for simultaneously and stably preparing nanobubble-containing pure water and microbubble-containing concentrated brine, and belongs to the technical field of water treatment. The device comprises a booster pump, a reverse osmosis membrane assembly, a pure water tank and a concentrated brine tank. The inlet of the booster pump is connected with a water inlet pipe, the outlet of the booster pump is connected with a water outlet pipe, a gas pipe is connected with the water inlet pipe or the water outlet pipe, the gas pipe is connected with a gas source, a pre-filter is arranged on the water inlet pipe and connected with a water source, the water outlet end of the water outlet pipe is connected with the water inlet of the reverse osmosis membrane assembly, the concentrated brine outlet of the reverse osmosis membrane assembly is connected with the concentrated brine tank through a concentrated brine pipe, a concentrated brine adjusting valve is arranged on the concentrated brine pipe, and the pure water outlet of the reverse osmosis membrane assembly is connected with the pure water tank through a pure water pipe. The reverse osmosis membrane assembly is vertically arranged, the height of the water inlet of the reverse osmosis membrane assembly is lower than that of the concentrated brine outlet, no resistance element is arranged on the pure water pipe, and the pure water pipe is directly connected with the pure water tank. The device can stably and simultaneously obtain nanobubble-containing pure water and microbubble-containing concentrated brine at one time.

Description

Technical Field

[0001] This invention relates to an apparatus for producing pure water, and more particularly to an apparatus for simultaneously producing pure water containing nanobubbles and concentrated brine containing microbubbles, belonging to the field of water treatment technology. Background Technology

[0002] Pure water, also known as purified water, refers to high-purity water produced through reverse osmosis membranes (RO membranes) that contains only water molecules and no impurities. It has a wide range of applications in daily life and production.

[0003] It is known that existing methods for producing water with micro-nano bubbles generally use traditional dissolved air release methods via aerators or jet injectors. The water used to generate these micro-nano bubbles is ordinary water, not purified water or concentrated brine obtained through reverse osmosis (RO) membranes. Currently, the main purpose of producing water with micro-nano bubbles is to rinse stains on filter membranes. For example, Chinese Patent CN110776158A discloses a water purification device and its usage method, which uses a pump to pressurize water mixed with gas, and then releases the pressurized gas from the water through a micro-nano bubble generating component (actually an aerator) in a second outlet pipe to form micro-nano bubble water. This micro-nano bubble water is then used to clean the filter cartridge. Existing methods for producing water with micro-nano bubbles must be done separately; they cannot be produced simultaneously with the process of producing purified or even pure water. That is, either the production of purified water must be stopped while the production of micro-nano bubble water is stopped, or the production of micro-nano bubble water must be stopped while the production of purified water is stopped. The production of purified water and the production of micro-nano bubble water must be carried out separately.

[0004] Current methods for producing pure water containing micro / nano bubbles involve separately preparing pure water and micro / nano gas, then introducing the micro / nano gas into the pure water to obtain pure water with micro / nano bubbles. For example, the "Nano Bubble Hydrogen-Rich Water Direct Drinking Machine" published in Chinese Patent Publication No. CN216472666U extrudes large-molecule hydrogen gas from a microporous structure into 10nm-10μm nano-sized hydrogen bubbles, which are then injected into pre-prepared and stored pure water to form hydrogen-rich water. However, this existing method does not simultaneously produce pure water containing micro / nano bubbles in a single process; it cannot simultaneously introduce nano-bubbles into the pure water during the production of pure water.

[0005] There is no existing technology that can simultaneously produce pure water containing nanobubbles and concentrated brine containing microbubbles using reverse osmosis membranes, nor is there any equipment that can achieve a high wastewater ratio to simultaneously produce pure water containing nanobubbles and concentrated brine containing microbubbles. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to simultaneously and stably obtain pure water containing nano-bubbles and concentrated brine containing micro-bubbles in one step using a reverse osmosis membrane (RO membrane).

[0007] The technical solution proposed by this invention to solve the above-mentioned technical problems is as follows: an apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine, comprising a booster pump, a reverse osmosis membrane module, a pure water tank and a concentrated brine tank. The inlet of the booster pump is connected to an inlet pipe, and the outlet of the booster pump is connected to an outlet pipe. An air pipe is connected to either the inlet pipe or the outlet pipe, and the air pipe is connected to an external air source. A pre-filter is installed on the inlet pipe and connected to an external water source. The outlet port of the outlet pipe is connected to the inlet of the reverse osmosis membrane module. The concentrated brine outlet of the reverse osmosis membrane module is connected to the concentrated brine tank through a concentrated brine pipe. A concentrated brine regulating valve is installed on the concentrated brine pipe. The pure water outlet of the reverse osmosis membrane module is connected to the pure water tank through a pure water pipe. The reverse osmosis membrane module is vertically positioned with its inlet height lower than its concentrated brine outlet height. The pure water pipe has no resistance components and leads directly to the pure water tank.

[0008] The mechanism and beneficial effects of the technical solution of this invention are as follows: 1. When the booster pump injects the gas-liquid two-phase mixed fluid into the reverse osmosis membrane module through the inlet, a portion of the gas-liquid two-phase mixed fluid passes through the membrane pores of the reverse osmosis membrane under the action of pressure difference. The air bubbles in this portion of the fluid are cut and broken by the membrane pores of the reverse osmosis membrane to form nanobubbles. At the same time, impurities in the water in this portion of the fluid are blocked. What is obtained through the membrane pores of the reverse osmosis membrane is pure water containing nanobubbles.

[0009] 2. When the other part of the gas-liquid two-phase mixed fluid passes through the gap between each two rolls of the reverse osmosis membrane under pump pressure, the feed water separator set between each two rolls is made of woven warp and weft threads. The thickness of the feed water separator is generally less than 1 mm, reaching the micron level. Therefore, when this other part of the mixed fluid passes through the feed water separator, on the one hand, the air bubbles in the fluid are squeezed into micron bubbles, thus forming concentrated water containing micron bubbles; on the other hand, the concentrated water containing micron bubbles will form turbulence when passing through the feed water separator, thus continuously and violently scouring the surface of the reverse osmosis membrane. As long as the booster pump is working, this scouring of the reverse osmosis membrane surface continues, thus ensuring that the surface of the reverse osmosis membrane is always in a relatively clean state (high permeability of membrane pores) during the reverse osmosis water production process, thereby ensuring the quality of pure water output.

[0010] 3. Since the reverse osmosis membrane module is vertical and its inlet height is lower than the concentrated brine outlet height, the mixed fluid at the pump outlet enters from the bottom of the reverse osmosis membrane module and exits from the top. This allows air bubbles in the fluid that do not pass through the reverse osmosis membrane pores and air bubbles in the fluid that pass through the gaps in the reverse osmosis membrane layers to form air flotation and rise rapidly to the concentrated brine outlet for discharge. Therefore, the resistance at the pump outlet can be greatly reduced, ensuring the stable operation of the entire device while producing pure water containing nano-bubbles and concentrated brine containing micron-bubbles.

[0011] 4. Because the pure water pipe has no resistance components and connects directly to the pure water tank, the nanobubbles formed through the membrane pores of the reverse osmosis membrane can quickly flow into the pure water tank without accumulating at the reverse osmosis membrane and creating resistance to the overall fluid flow. The smaller the bubbles in the water, the greater the total dissolved air volume; the total dissolved air volume in water with nanobubbles is very large. Therefore, if they accumulate at the reverse osmosis membrane, the resistance will be very high, severely reducing the water permeability of the reverse osmosis membrane and causing it to malfunction.

[0012] 5. Due to the combination of the effects of points 2, 3 and 4 above, the pump can operate stably and produce pure water containing nano-bubbles and concentrated brine containing micron-bubbles under stable operating pressure.

[0013] 6. It is important to further explain that: Since water generally flows from top to bottom to facilitate the removal of concentrated water, the inlet height of existing vertical reverse osmosis membrane modules is always higher than the outlet height of the concentrated brine. This is the conventional setting for existing vertical reverse osmosis membrane modules. However, when a gas-liquid two-phase mixture containing gas is introduced into an existing vertical reverse osmosis membrane module, the air bubbles in the mixture accumulate inside the membrane, creating significant resistance. Therefore, existing vertical reverse osmosis membrane modules cannot function properly to produce pure water or concentrated brine (wastewater). This invention, by lowering the inlet height compared to the concentrated brine outlet height, completely overcomes the conventional setting of existing vertical reverse osmosis membrane modules. Furthermore, it achieves the unexpected effect of rapid air flotation as the pressurized mixture flows upwards, resolving the resistance caused by air bubble accumulation inside the reverse osmosis membrane. This allows the gas-liquid two-phase mixture to flow smoothly within the reverse osmosis membrane, ensuring its normal operation and simultaneously producing pure water containing nano-bubbles and concentrated brine containing micron-bubbles. Furthermore, as the concentrated brine containing micron-sized air bubbles passes between the two reverse osmosis membranes under the influence of buoyancy and pump pressure, it continuously and effectively washes the surface of the reverse osmosis membranes throughout operation. This ensures that the reverse osmosis membranes are cleaned of impurities and contaminants in the water while producing pure water, thus maintaining a high permeability during operation and guaranteeing the quality of the pure water output. In addition, because of the continuous and effective washing of the reverse osmosis membrane surface by the concentrated brine containing micron-sized air bubbles, this invention can operate at high concentration-to-water ratios (wastewater to pure water to concentrated brine ratio) and almost eliminates the need for backwashing of the reverse osmosis membranes when not in operation, thereby significantly improving water efficiency.

[0014] Furthermore, the gas source is any one of air, oxygen, ozone, and hydrogen.

[0015] Furthermore, when an air pipe is connected to the water outlet pipe, the pressure inside the air pipe must be greater than or equal to the outlet pressure of the booster pump. In the case where gas is added to the water outlet of the booster pump, the pressure of the external air source must be greater than or equal to the outlet pressure of the booster pump.

[0016] Furthermore, the concentrated brine containing micron-sized bubbles produced by the device of the present invention can be used to clean vegetables and fruits.

[0017] Furthermore, the resistance element is a valve, tee, multi-way valve, pressure gauge, or flow meter. Attached Figure Description

[0018] The apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine according to the present invention will be further described below with reference to the accompanying drawings.

[0019] Figure 1 This is a flow chart of an apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine, as described in Example 1.

[0020] Figure 2 This is a flow chart of an apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine, as described in Example 2. Detailed Implementation

[0021] Example 1 This embodiment provides an apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine, comprising a booster pump 1, a reverse osmosis membrane module 2, a pure water tank 10, and a concentrated brine tank 11. The booster pump 1 has an inlet pipe 12 connected to its inlet and an outlet pipe 18 connected to its outlet. An air pipe 13 is connected to the inlet pipe 12 and is connected to an external air source. A pre-filter 6 is installed on the inlet pipe 12 and connected to an external water source. The outlet port of the outlet pipe 18 is connected to the inlet 14 of the reverse osmosis membrane module 2. In this embodiment, the inlet pipe 12 is also equipped with a water valve 5 and a one-way water valve 7. The air pipe 13 is also equipped with an air valve 9 and a one-way air valve 8. The concentrated brine outlet 15 of the reverse osmosis membrane module 2 is connected to the concentrated brine tank 11 via a concentrated brine pipe 16. The concentrated brine pipe 16 is equipped with a concentrated brine regulating valve 3, a bypass valve, and a bypass valve 4 for controlling the ratio between pure water and concentrated brine. The pure water outlet of the reverse osmosis membrane module 2 is connected to the pure water tank 10 via a pure water pipe 17. The reverse osmosis membrane module 2 is vertically mounted, and the height of the inlet 14 of the reverse osmosis membrane module 2 is lower than the height of the concentrated brine outlet 15. No obstructions (such as valves, tees, multi-way valves, pressure gauges, and flow meters) are installed on the pure water pipe 17, which leads directly to the pure water tank 10.

[0022] During use, the inlet of booster pump 1 draws in water mixed with gas. When booster pump 1 pumps this mixed fluid into reverse osmosis membrane module 2, a portion of the mixed fluid passes through the membrane pores of the reverse osmosis membrane under the action of pressure difference. The bubbles in this portion of the fluid are cut and broken by the membrane pores of the reverse osmosis membrane to form nanobubbles. At the same time, impurities in the water in this portion of the fluid are blocked. What is obtained through the membrane pores of the reverse osmosis membrane is pure water containing nanobubbles directly. 2. When another portion of the mixed fluid passes through the gap between each two rolls of the reverse osmosis membrane under the pump pressure of booster pump 1, since the gap between each two rolls is a micron-level gap, the bubbles in this other portion of the mixed fluid are squeezed into micron-sized bubbles to form concentrated brine containing micron-sized bubbles.

[0023] The gas source in this embodiment can be any one of air, hydrogen, oxygen, and ozone. For example: 1) Using air, we obtain pure water containing nano-sized air bubbles and concentrated salt water containing micron-sized air bubbles; 2) Using oxygen yields pure water containing nano-oxygen bubbles and concentrated salt water containing micron-oxygen bubbles; 3) Using ozone, we obtain pure water containing nano ozone bubbles and concentrated salt water containing micron ozone bubbles; 4) Using hydrogen gas yields pure water containing nano-sized hydrogen bubbles and concentrated salt water containing micron-sized hydrogen bubbles.

[0024] Experimental comparison The experiment using an existing reverse osmosis membrane pure water machine is the first type of experiment; the experiment using the apparatus of this embodiment but with the reverse osmosis membrane module arranged in the existing normal configuration (i.e., the height of the inlet is normally higher than the height of the concentrated brine outlet) is the second type of experiment; the experiment using the apparatus of this embodiment entirely is the third type of experiment; the three experimental scenarios are as follows: Experimental conditions: The booster pump used was Delta 205-200A; the reverse osmosis membrane used was Huitong ULP2012-100; the gas source was an SPE electrolyzer producing hydrogen with a flow rate of 100 ml / min (electrolysis current ≈ 13.5 A); the TDS of the raw water was ≈ 116~123; in all three experiments, the concentrated brine regulating valve was adjusted to make the pure water outlet flow rate about 500 ml / min and the wastewater flow rate about 100 ml / min, that is, in all three experiments, the wastewater ratio of the concentrated brine regulating valve 3 was maintained at 1:5.

[0025] Table 1 shows the experimental results of the first type using a conventional reverse osmosis membrane pure water machine. Table 2 shows the experimental results of the second type using the device of this embodiment but with the reverse osmosis membrane components arranged in the existing normal manner. Table 3 shows the experimental results of the third type using the device of this embodiment.

[0026] Table 1 Analysis of the first experiment in Table 1 shows that: 1) The TDS of the "purified water" effluent exceeded 10 from the beginning of operation, indicating that under a 1:5 wastewater ratio, the existing conventional reverse osmosis membrane pure water machine could no longer operate normally to produce pure water. Although the flow rate did not decrease, the output was impure water. 2) Even with a 1:5 wastewater ratio, the TDS of the concentrate was not high, indicating that the fouling on the RO membrane was quite severe. 3) The pump outlet pressure was 0.8 and the current was 2.12A, indicating that the pump was under heavy load.

[0027] Table 2 Analysis of the second experiment in Table 2 shows that: 1) Although it could initially produce purified water (TDS was below the pure water standard, hence the name "purified water"), the purified water flow rate decreased significantly over time, while the TDS rose above 10, making it impossible to produce purified water. 2) The pump outlet pressure was 0.7A and the current was 0.78A, indicating that after prolonged operation, the pump became filled with air, causing a decrease in the pump's operating current and consequently a decrease in the water flow rate. Therefore, the apparatus in the second experiment could not continue to operate normally.

[0028] Table 3 Analysis of the third experiment in Table 3 shows that: ① Compared to the first experiment, in this experiment, under the gas-liquid two-phase flow condition, the pump pressure decreased from 0.8 MPa to 0.7 MPa, and the current also dropped from 2.12 A to 1.5–1.6 A. This means that the pump load of this experimental setup is lighter, which is beneficial for pump operation. Although the flow rate of "pure water" in the first experiment did not change much, the output was all impure water, therefore it is not comparable to the pure water in this experiment.

[0029] ② As the operating time of this experimental setup increased, the TDS of the concentrate continued to increase, and the absolute value of the concentrate TDS was much greater than that of the concentrate TDS in the first experiment in Table 1. This indicates that this experimental setup has extremely strong immediate descaling capabilities, and it is difficult for fouling to accumulate on the membrane surface.

[0030] ③ In fact, this experiment lasted much longer than 60 minutes. The apparatus used in this experiment has been running continuously with a new 100G membrane since the Spring Festival of 2021 (it is shut down during holidays). It works continuously from 8:00 to 16:00 every day (the bypass valve 4 is opened every hour for 4 seconds to flush and it can work normally). The average TDS of the municipal tap water is 110-130, and the TDS of the effluent is always less than 10. While maintaining a wastewater ratio of 1:5, the effluent flow rate is stable at 450-520 ml / min. Apart from replacing the pre-filter PP cotton, the pump, RO membrane, and hydrogen electrolyzer have all been working normally since the experiment.

[0031] Furthermore, the backwashing results in the first experiment using an existing reverse osmosis membrane pure water machine are compared with the backwashing results in the third experiment using the device of this embodiment, as shown in Table 4 below.

[0032] Table 4 Analysis of Table 4 shows that the backwash water volume required by conventional pure water machines is much greater than that required by the device in this embodiment. This is because, as mentioned above, the device in this embodiment utilizes microbubbles and concentrated brine to flush the RO membrane, making it difficult for dirt to adhere to the membrane. Therefore, the backwash water consumption is extremely low and the time is very short, only 4 seconds per hour, which is negligible compared to the amount of pure water produced. Consequently, the device in this embodiment can maintain a high wastewater ratio (1:5) while still producing compliant pure water, demonstrating high water efficiency.

[0033] In summary: 1) The device of this embodiment can simultaneously produce pure water containing nanobubbles and concentrated brine containing microbubbles in one operation, and the output of pure water and concentrated brine is the most stable, maintaining a stable output of pure water and concentrated brine over time. 2) Existing reverse osmosis membrane pure water machines cannot operate normally when the wastewater ratio is as high as 1:5; similarly, the second experimental device also cannot operate normally as the operating time increases. 3) The device of this embodiment consumes very little water and takes very little time for backwashing, therefore its water efficiency is far higher than that of existing reverse osmosis membrane pure water machines, and it can maintain normal operation even with a high wastewater ratio.

[0034] Example 2 The apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine in this embodiment is a variation based on Embodiment 1, such as... Figure 2 As shown, the differences from Embodiment 1 are: 1) The gas pipe 13 is replaced by a connection to the outlet pipe 18 of the booster pump 1, meaning the outlet pipe 18 of the booster pump 1 is connected to an external gas source via the gas pipe 13. This ensures that a gas-liquid two-phase mixture is also obtained within the outlet pipe 18 of the booster pump 1, and then flows into the reverse osmosis membrane module 2 from the inlet 14. 2) A one-way water valve 7 is installed on the outlet pipe 18. 3) Since gas is added to the water at the booster pump outlet, the pressure of the external gas source must be greater than or equal to the outlet pressure of the booster pump.

[0035] The results of the fourth experiment conducted using the apparatus of this embodiment are shown in Table 5 below.

[0036] Table 5 Compared with the device in Embodiment 1, the pure water and concentrated water indicators of this embodiment are similar. However, due to the addition of air at the pump outlet, the pump pressure and pump operating current are increased (load is increased), but this does not result in a significant increase in the output flow rate of pure water and concentrated water. The concentrated brine containing micron-sized bubbles obtained in the above two embodiments has another use: for cleaning vegetables and fruits.

[0037] The above description is only a preferred embodiment of the present invention, but the present invention is not limited thereto. All equivalent substitutions or modifications made to the concepts and technical solutions of the present invention should be covered within the protection scope of the present invention.

Claims

1. An apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine, comprising a booster pump, a reverse osmosis membrane module, a pure water tank, and a concentrated brine tank; the booster pump has an inlet pipe connected to its inlet and an outlet pipe connected to its outlet; an air pipe is connected to either the inlet or outlet pipe, the air pipe being connected to an external air source; a pre-filter is installed on the inlet pipe and connected to an external water source; the outlet of the outlet pipe is connected to the inlet of the reverse osmosis membrane module; the concentrated brine outlet of the reverse osmosis membrane module is connected to the concentrated brine tank via a concentrated brine pipe; a concentrated brine regulating valve is installed on the concentrated brine pipe; and the pure water outlet of the reverse osmosis membrane module is connected to the pure water tank via a pure water pipe; characterized in that: The reverse osmosis membrane module is placed vertically with its inlet height lower than its concentrated brine outlet height, and the pure water pipe has no resistance components and connects directly to the pure water tank.

2. The apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine according to claim 1, characterized in that: The gas source is any one of air, hydrogen, oxygen, and ozone.

3. The apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine according to claim 1, characterized in that: When an air pipe is connected to the water outlet pipe, the pressure inside the air pipe is greater than or equal to the outlet pressure of the booster pump.

4. The apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine according to claim 1, characterized in that: The micron-sized bubble-concentrated brine is used to clean vegetables and fruits.

5. The apparatus for simultaneously and stably producing nanobubble pure water and microbubble concentrated brine according to claim 1, characterized in that: The resistance component is a valve, multi-way valve, pressure gauge, or flow meter.

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