A dissolved air flotation water purification device

Abstract

The application provides a dissolved air floatation water purification device, and relates to the technical field of water treatment. The device comprises a mixer, a constant-pressure dissolved air tank, a micro-bubble releaser, a floatation reaction zone and the like. Raw water enters the system from the inlet end of the mixer, and the outlet end is connected with a booster pump. The mixer is provided with a dosing opening, and the dosing opening is connected with a dosing metering device. The outlet end of the booster pump is connected with the water inlet end of the constant-pressure dissolved air tank, the outlet end of the air source equipment is connected with the air inlet end of the constant-pressure dissolved air tank, and the water outlet end of the constant-pressure dissolved air tank is connected with the dissolved air micro-bubble releaser. The dissolved air water is subjected to sufficient and complete floatation reaction in the contact chamber and the separation chamber, and the upper floatation impurities are removed by the slag scraping plate. The application has the advantages of high dissolved air efficiency, good air releasing effect and high automation degree.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a dissolved air flotation water purification device. BACKGROUND

[0002] The conventional water purification process of raw water-coagulation-sedimentation-filtration-disinfection has been difficult to treat special contaminated water, and often the quality of finished water does not meet the standards. Even if the amount of reagent is increased, the treatment coagulation effect is poor, the formed floc particles are small, and the floc particles are difficult to precipitate. At present, many water plants have gradually adopted the air flotation process to solve such water source problems.

[0003] The air flotation method is to pass a large amount of micro-bubbles into the water, which adhere to the impurity floc particles to form a whole with a specific gravity less than water, and rely on the buoyancy to float to the water surface. The conventional air flotation process device forcibly dissolves gas in water by air compressor or gas-liquid mixing pump, and then releases it in the air flotation device through the pipeline: the conventional air flotation gas tank generally only controls the pressure in the tank by adjusting the liquid level, and it is difficult to ensure that the gas-liquid two-phase reaches the equilibrium solubility or saturated solubility, which results in relatively less gas dissolved in water; some even directly pass high-pressure gas into the air flotation tank, and the air flotation effect is not obvious, which is easy to cause less scum, poor water quality and other problems. However, due to the problems of uneven local pressure and large volume of gas bubbles remaining in the forced pressurized gas-liquid mixing process, the air flotation separation effect is poor, which directly affects the removal effect of suspended solids and iron and manganese ions; the conventional release device also has the defects of poor energy dissipation effect, serious turbulence, non-uniform diameter of released gas bubbles, and is easy to be blocked, which seriously affects the air flotation effect.

[0004] The present application provides a dissolved air flotation water purification device, which mixes gas and liquid sufficiently in a constant pressure gas dissolving tank, and the gas-liquid two-phase mixture has the characteristics of high gas content and no large particle gas bubbles. After the dissolved air water is released from the micro-bubble release device, the diameter of the gas bubbles is less than 20 microns, which can effectively adsorb the solid particles in the gas-liquid mixture to float to the water surface, so that the solid-liquid is well separated, and the water source pollution problem of water plants is effectively solved. SUMMARY

[0005] (I) Technical problems solved

[0006] In view of the deficiencies of the prior art, the present application provides a dissolved air flotation water purification device to solve the problems raised in the background art.

[0007] (II) Technical solutions

[0008] In order to achieve the above object, the present application is realized by the following technical scheme: a dissolved air flotation water purification device: comprising a booster pump, a constant pressure dissolved air tank, a microbubble releaser, a flotation reaction zone, a control center, the outlet end of the booster pump is connected to the water inlet end of the constant pressure dissolved air tank, the air inlet end of the constant pressure dissolved air tank is also connected with an air source, the water outlet end of the constant pressure dissolved air tank is connected with a dissolved air microbubble releaser, the flotation reaction zone is divided into a contact zone, a separation zone and a water outlet zone, and a residue discharge zone, the water outlet end of the constant pressure dissolved air tank is connected with the dissolved air microbubble releaser, the dissolved air microbubble releaser is arranged in the contact zone, a transmission device and a control system are arranged above the flotation reaction zone, a residue scraping plate is arranged at the front end of the transmission device, the transmission device is linked with the residue scraping plate, a water quality detector is arranged at the front end of the residue scraping plate, water quality data is transmitted to the transmission control system, and the transmission device is controlled to start and stop and move at a frequency by the transmission control system; the booster pump, the air source and the control center are electrically connected, raw water enters through the water inlet end of the constant pressure dissolved air tank and flows into the microbubble releaser from the water outlet end thereof, sufficient and complete flotation reaction occurs in the contact zone and the separation zone, and the upper flotation impurities are removed by the residue scraping plate.

[0009] Preferably, a mixer is arranged in the pipeline before the booster pump, the mixer comprises a dosing port, the dosing port is connected with a dosing metering device, and the dosing metering device is electrically connected with the control center.

[0010] Preferably, an electromagnetic flowmeter one is arranged in the pipeline before the mixer, a water quality detector one is arranged between the electromagnetic flowmeter one and the mixer, and the electromagnetic flowmeter one and the water quality detector one are electrically connected with the control center.

[0011] Preferably, the upper end of the constant pressure dissolved air tank is an air source zone, a filler zone is additionally arranged in the middle, and the lower end is a liquid source zone, the air source zone is provided with an adjustable air bag, a pressure sensor and an electric exhaust valve, the liquid source zone is provided with a level meter, and the adjustable air bag, the electric exhaust valve, the pressure sensor and the level meter are electrically connected with the control center, so that constant pressure and microbubble dissolved air are realized through comprehensive control of the controller center, and gas-liquid two-phase mixing is fully realized.

[0012] Preferably, the microbubble releaser is provided with a decompression cavity, the decompression cavity is in the form of a boss, a plurality of release pipes are arranged at equal angles around the decompression cavity, a bubble generator is arranged in each release pipe, after the dissolved air water enters the release pipe and passes through the bubble generator, the energy of the bubbles is avoided, and the flotation effect is ensured.

[0013] Preferably, the lower end of the separation zone is provided with a backflow port backflowing to the constant-pressure dissolved gas tank, and the backflow port is connected with an electromagnetic flowmeter II and a regulating electric valve, which are electrically connected with the control center; when the water quality is poor or the air flotation effect is not obvious, partial backflow can be adopted, the clean water backflow ratio is 5-10%, and the sewage backflow ratio is 15-30%.

[0014] Preferably, a flocculation device can be added between the mixer and the booster pump.

[0015] Preferably, a precipitation device can be arranged in the separation zone to strengthen the flocculation effect.

[0016] (Three) beneficial effects

[0017] The application provides a dissolved air flotation water purification device, which has the following beneficial effects:

[0018] 1. The constant-pressure dissolved gas tank of the dissolved air flotation water purification device controls the gas phase partial pressure in real time, timely increases the gas phase fluid density, reduces the bubble particle size, improves the surface renewal rate, increases the liquid phase spraying density, accelerates the liquid flow speed, reduces the liquid film thickness, adds the filler bed to intensify the liquid phase turbulence degree, increases the actual contact area of the two phases, prolongs the contact time of the two phases, and the dissolved gas rate reaches 90%.

[0019] 2. The micro-bubble releaser of the dissolved air flotation water purification device shortens the hydraulic retention time of the high-resistance area, utilizes the decompression cavity and the release pipe, reduces the turbulent large vortex street or horse tail vortex street caused by high-speed fluid injection, effectively reduces the bubble collision probability, moves the bubble gathering process to outside the release port, improves the air flotation reaction efficiency, and the released bubble particle size is less than 20 microns.

[0020] 3. The dissolved air flotation water purification technology of the dissolved air flotation water purification device can be combined with a flocculation tank or a precipitation, and greatly solves the problems that the conventional water purification plant process cannot remove oil, algae-containing water, low-turbidity water and micro-polluted water and the like. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a process principle diagram of the dissolved air flotation water purification device of the application;

[0022] Figure 2 It is a structure schematic view of the liquid phase sprayer in the constant-pressure dissolved gas tank of the application;

[0023] Figure 3 It is a top view of the micro-bubble releaser of the application;

[0024] Figure 4 It is a front view of the micro-bubble releaser of the application;

[0025] Figure 5 It is a dissolved gas mode schematic view of the application.

[0026] In the diagram: 1. Booster pump; 2. Constant pressure dissolved air tank; 201. Water inlet; 202. Air inlet; 203. Electric exhaust valve; 204. Pressure sensor; 205. Water outlet; 206. Vent port; 207. Atomizing wide-angle sprayer; 208. Spray nozzle; 21. Air source area; 211. Inspection window; 212. Adjustable air bag; 213. Packed bed; 22. Liquid source area; 221. Level gauge; 23. Control center; 3. Air source; 4. Mixer; 41. Electric... Magnetic flowmeter 1; 42. Water quality analyzer 1; 43. Dosing and metering device; 5. Air flotation reaction zone; 50. Microbubble releaser; 501. Pressure reducing chamber; 502. Release pipe; 51. Contact zone; 52. Separation zone; 522. Second guide plate; 523. Transmission device; 524. Control system; 525. Sludge scraper; 526. Water quality analyzer 2; 53. Effluent zone; 54. Sludge discharge zone; 55. Electromagnetic flowmeter 2; 551. Return port; 56. Regulating electric valve. Detailed Implementation

[0027] This invention provides a dissolved air flotation water purification device, such as... Figures 1-5 As shown, the system includes a mixer 4, a constant-pressure dissolved air tank 2, a microbubble releaser 50, and an air flotation reaction zone 5. Raw water enters the system from the inlet of the mixer 4, and the outlet is connected to a booster pump 1. The mixer 4 includes a dosing port connected to a dosing metering device 43. The outlet of the booster pump 1 is connected to the inlet 201 of the constant-pressure dissolved air tank 2, and the outlet of the air source 3 is connected to the inlet 202 of the constant-pressure dissolved air tank 2. The outlet 205 of the constant-pressure dissolved air tank 2 is connected to the dissolved air microbubble releaser 50. The dissolved air water undergoes a complete air flotation reaction in the contact chamber and separation chamber, and a scraper 525 removes the upper air flotation impurities. This invention has advantages such as high dissolved air efficiency, good air release effect, and high degree of automation.

[0028] Preferably, the constant pressure dissolved gas tank 2 is equipped with an adjustable air bag 212, a pressure sensor 204, and an electric exhaust valve 203 in the gas source area 21, and a level gauge 221 in the liquid source area 22. A packing area is added in the middle. Constant pressure and microbubble dissolved gas are achieved through the comprehensive control of the controller center, and the gas and liquid phases are fully mixed.

[0029] Preferably, the microbubble releaser 50 is provided with a pressure reducing chamber 501, which restricts the vortex formed by the high-speed water flow at the outlet of the boss through hole as much as possible within the pressure reducing chamber 501. After the dissolved air water enters the release pipe 502 and passes through the bubbler, the energy dissipation of the bubbles is avoided, thus ensuring the air flotation effect.

[0030] Preferred, such as Figure 1 As shown in the lower right corner, when the influent water quality is poor or the flotation effect is not obvious, a partial recirculation method can be adopted, with a clean water recirculation ratio of 5-10% and a wastewater recirculation ratio of 15-30%.

[0031] Preferably, when the raw water can complete the air flotation process efficiently without the need for chemical addition, the mixer 4 and the chemical dosing device can be omitted.

[0032] Preferably, a flocculation (grid / baffle / mechanical flocculation, etc.) device can be added between the mixer 4 and the booster pump 1, and the separation zone 52 can be combined with a sedimentation (inclined tube / baffle / horizontal flow / radial flow sedimentation, etc.) device to enhance the flocculation effect.

[0033] The raw water is pressurized by a water pump and, together with pressurized air, is forced into a sealed, constant-pressure dissolved air tank 2. The turbulent flow of water and air causes the gas to dissolve in the water (excess undissolved air is discharged through an electric exhaust valve 203). The dissolved air water is abruptly depressurized by a microbubble releaser 50, which causes microbubbles to be released stably and adhere to impurities in the water, floating to the surface together. The scum is discharged into a scum tank by a scum scraper, while the clear water flows out from the bottom.

[0034] Implementation Case 1:

[0035] The key to determining the degree to which a gas dissolves in a liquid lies in the partial pressure of the gas phase in contact with the liquid phase. This partial pressure must be maintained higher than the partial pressure generated in the liquid phase for the gas transfer process to continue. Therefore, continuously monitoring and ensuring that the gas phase partial pressure is within the ideal value is the primary task of dissolved gas flotation.

[0036] This invention primarily involves installing a pressure sensor 204 and an adjustable air bladder 212 in the gas source area 21 of the constant-pressure dissolved gas tank 2, and a level gauge 221 in the liquid source area 22. The pressure sensor 204 and level gauge 221 are mainly used to monitor the pressure value inside the constant-pressure dissolved gas tank 2 and feed it back to the controller center. The controller center, considering the ideal partial pressure of the gas phase, controls the expansion of the adjustable air bladder 212 to ensure that the partial pressure of the gas phase in the constant-pressure dissolved gas tank 2 is maintained near a preset value. If the pressure exceeds the preset value, the controller center activates the electric exhaust valve 203 to release air. The intermittent expansion and contraction of the adjustable air bladder 212 can appropriately increase the fluid density, reduce bubble particle size, improve the surface renewal rate, and accelerate the dissolved gas rate.

[0037] In the two-film theory, the liquid film resistance is hundreds of times greater than the gas film resistance, which is negligible. Therefore, the gas dissolution process is primarily controlled by the liquid film. Furthermore, increasing the liquid phase velocity and turbulence helps reduce the liquid film thickness and accelerate the gas transfer rate.

[0038] like Figure 2 As shown, the present invention also includes an atomizing wide-angle sprayer 207 installed at the inlet of the constant pressure dissolved air tank 2, with dozens of micro-spray nozzles 208 installed inside the wide-angle sprayer. The design of the wide-angle sprayer allows pressurized water to enter the constant pressure dissolved air tank 2 in a fine mist, and most importantly, it can increase the liquid phase spray density, accelerate the liquid flow rate, reduce the liquid film thickness, and accelerate the dissolved air rate.

[0039] The constant pressure dissolved gas tank 2 is additionally provided with the filler bed 213, so that the liquid phase turbulence degree can be intensified, the actual contact area of the two phases is increased, the actual contact time of the two phases is prolonged, the surface renewal rate is increased, and the dissolved gas rate is accelerated.

[0040] Case 2:

[0041] Only good dissolved gas effect, without good release conditions (such as insufficient bubble release or too dilute or large released bubbles), is still in vain. The design of the microbubble release device 50 quickly gathers into numerous ultra-micro bubbles (diameter less than 20 microns) of different sizes after instantaneous pressure reduction, energy dissipation, mass transfer and gas release, and continues to collide and gradually increase in size in the intense turbulent diffusion and molecular diffusion.

[0042] As shown in Figure 3 and 4 , the dissolved gas water enters the subsequent microbubble release device 50 first into the pressure reduction cavity 501, the purpose is to limit the vortex street formed by the high-speed water flow of the boss through hole outlet in the pressure reduction cavity 501 as much as possible, and then the dissolved gas water enters the release pipe 502; the end of the release pipe 502 is provided with a bubbler; at this time, there are a large number of fine bubbles of about 1-10 microns in the water, and the bubbles further merge to form 10-20 micron bubbles after passing through the area with small speed gradient and long residence time of the release pipe 502. In fact, the setting of the release pipe 502 makes the bubble size larger, but if the release pipe 502 is removed, the high-speed water flow of the boss through hole outlet will directly enter the water body, forming a large turbulent vortex street or horse tail vortex street, causing the bubble collision probability to increase rapidly, resulting in a larger bubble size than when the release pipe 502 is set. Therefore, the setting of the release pipe 502 and the bubbler can to some extent alleviate the energy dissipation of the bubbles and avoid the situation of turbulent flow and vortex flow.

[0043] The microbubble release device 50 shortens the hydraulic residence time of the high-resistance area, and uses the pressure reduction cavity 501 and the release pipe 502 to reduce the turbulent vortex street or horse tail vortex street caused by high-speed fluid injection, effectively reduces the bubble collision probability, and moves the bubble gathering process to outside the release device outlet. Compared with the 20-40 micron bubbles formed by the traditional dissolved air flotation release device, the device can form a large number of bubbles below 20 microns, the required gas amount is small, the specific surface area is large, and the air flotation effect is better.

[0044] From the above description, it can be seen that the above-mentioned embodiments of the present application achieve the following technical effects: in the constant pressure dissolved gas tank 2, the gas-liquid two phases can be fully mixed, and the dissolved gas filtration rate can reach more than 90%; in the microbubble release device 50, the bubble diameter can be less than micron, the bubbles are fine and uniform, which is obviously better than the traditional dissolved air flotation method, and can solve the problems of low turbidity water and micro-organic pollution water in water purification plants.

[0045] Working principle: After the raw water enters the system, it first passes through the electromagnetic flowmeter. The water inlet end 201 of the mixer 4 is connected with the electromagnetic flowmeter. A water quality detector is arranged between the electromagnetic flowmeter and the mixer 4. The data of the electromagnetic flowmeter and the water quality detector are transmitted to the controller center. The dosing port of the mixer 4 is connected with the dosing metering device 43. The dosing amount, dosing time and the like of the dosing metering device 43 are controlled by the controller center. The controller center accurately calculates the dosing amount in combination with the water quality, water flow, dissolved air tank pressure and other parameters. The water outlet end 205 of the mixer 4 is connected with the water inlet end 201 of the booster pump 1. The start and stop of the booster pump 1 are controlled by the controller center. The water outlet end 205 of the booster pump 1 is connected with the water inlet end 201 of the constant pressure dissolved air tank 2. The water inlet end 201 is connected with the wide-angle sprayer. The wide-angle sprayer is provided with dozens of micro-spraying nozzles 208. The gas source 3 can be an air compressor or a fan. The gas outlet of the gas source 3 is connected with the gas inlet end 202 of the constant pressure dissolved air tank 2. The start and stop of the gas source 3 are controlled by the controller center. The upper part of the constant pressure dissolved air tank 2 is the gas source area 21. The lower part is the liquid source area 22. There is a filler bed 213 in the middle. The electric exhaust valve 203 and the pressure sensor 204 are installed in the gas source area 21. The pressure signal is transmitted to the controller center. The opening and closing of the electric exhaust valve 203 are controlled by the controller center. The level meter 221 is installed in the liquid source area 22. The level signal is transmitted to the controller center. The inside of the gas source area 21 of the constant pressure dissolved air tank 2 is provided with an adjustable air bag 212. The start and stop of the adjustable air bag 212 are controlled by the controller center. The upper part of the constant pressure dissolved air tank 2 is provided with a maintenance window 211. The lower end of the constant pressure dissolved air tank 2 is provided with the water outlet end 205 and the vent port 206. The dissolved air water flows into the air flotation reaction area 5 from the water outlet end 205. The air flotation reaction area 5 includes four areas, i.e. the contact area 51, the separation area 52, the water outlet area 53 and the residue discharge area 54. The first guide plate separates the contact area 51 and the separation area 52. The second guide plate 522 separates the separation area 52 and the water outlet area 53. The water outlet end 205 of the constant pressure dissolved air tank 2 is connected with the micro-bubble release device 50. After the dissolved air water enters the micro-bubble release device 50, it first enters the pressure reduction cavity 501 and then enters the release pipe 502. The release pipe 502 is provided with a bubbler. The released dissolved air water performs air flotation reaction in the contact area 51. The bubbles carry the residue to float. After entering the separation area 52, the clean water enters the water outlet area 53 from the lower part. The air flotation residue enters the residue discharge area 54. The upper part of the air flotation reaction area 5 is provided with a transmission device 523. The water quality detector is arranged at the front end of the residue scraping plate 525. The water quality data is transmitted to the transmission control system 524. The transmission device 523 is linked with the residue scraping plate 525. The transmission device 523 is controlled by the transmission control system 524 in terms of start and stop and movement frequency. The lower end of the air flotation reaction area 5 is provided with the backflow port 551. The backflow port 551 is connected with the electromagnetic flowmeter. The data of the electromagnetic flowmeter is transmitted to the controller center. The water outlet end 205 of the electromagnetic flowmeter is connected with the adjustable electric valve 56. The opening and closing degree is controlled by the controller center.

[0046] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A dissolved air flotation water purification apparatus, characterized by: The device comprises a booster pump (1), a constant pressure dissolved air tank (2), a microbubble releaser (50), a gas float reaction zone (5), and a control center (23). The outlet end of the booster pump (1) is connected to the water inlet end (201) of the constant pressure dissolved air tank (2). The air inlet end (202) of the constant pressure dissolved air tank (2) is also connected to an air source (3). The water outlet end of the constant pressure dissolved air tank (2) is connected to the dissolved air microbubble releaser (50). The gas float reaction zone (5) is divided into a contact zone (51), a separation zone (52), a water outlet zone (53), and a residue discharge zone (54). The microbubble releaser (50) is installed in the contact zone (51). A transmission device (523) and a control system (524) are provided above the gas float reaction zone (5). A residue scraping plate (525) is provided at the front end of the transmission device (523). The transmission device (523) is linked with the residue scraping plate (525). A water quality detector (526) is provided at the front end of the residue scraping plate (525). The water quality data is transmitted to the transmission control system (524). The transmission device (523) is controlled by the transmission control system (524) to start and stop and to change the moving frequency. The booster pump (1) and the air source (3) are electrically connected to the control center (23). Raw water enters the constant pressure dissolved air tank (2) through the water inlet end (201) and flows into the microbubble releaser (50) from the water outlet end (205). The dissolved air water undergoes sufficient and complete gas float reaction in the contact zone (51) and the separation zone (52). The upper gas float impurities are removed by the residue scraping plate (525). The upper end of the constant pressure dissolved air tank (2) is the air source zone (21). A filler zone (213) is additionally provided in the middle. The lower end is the liquid source zone (22). The air source zone (21) is provided with an adjustable air bag (212), an electric exhaust valve (203), and a pressure sensor (204). The liquid source zone (22) is provided with a level meter (221). The adjustable air bag (212), the electric exhaust valve (203), the pressure sensor (204), and the level meter (221) are electrically connected to the control center. The constant pressure and microbubble dissolved air are realized by the comprehensive control of the controller center (23), and the gas-liquid two-phase is fully mixed. The microbubble releaser (50) is provided with a pressure reduction cavity (501). The pressure reduction cavity (501) is in the form of a boss. A plurality of release pipes (502) are arranged at equal angles around the pressure reduction cavity (501). A bubble generator is arranged in the release pipe (502). After the dissolved air water enters the release pipe (502) and passes through the bubble generator, the bubble energy is avoided, and the gas float effect is ensured.

2. A dissolved air flotation water purification device according to claim 1, characterized in that: A mixer (4) is provided in the pipeline before the booster pump (1). The mixer (4) comprises a dosing port. The dosing port is connected to a dosing metering device (43). The dosing metering device (43) is electrically connected to the control center (23).

3. A dissolved air flotation water treatment device according to claim 2, wherein: An electromagnetic flowmeter (41) is provided in the pipeline before the mixer (4). A water quality detector (42) is provided between the electromagnetic flowmeter (41) and the mixer (4). The electromagnetic flowmeter (41) and the water quality detector (42) are electrically connected to the control center (23).

4. The dissolved air flotation water treatment device of claim 1, wherein: The lower end of the separation zone (52) is provided with a backflow port (551) backflowing to the constant-pressure dissolved gas tank (2), and the backflow port (551) is connected with an electromagnetic flowmeter two (55) and an adjusting electric valve (56), and the electromagnetic flowmeter two (55) and the adjusting electric valve (56) are electrically connected with the control center (23), when the water quality is poor or the air floating effect is not obvious, the partial backflow form can be adopted, the clean water backflow ratio is 5-10%, and the sewage backflow ratio is 15-30%.

5. The dissolved air flotation water purification device according to claim 2, characterized in that: The flocculation device can be added between the mixer (4) and the booster pump (1).

6. The dissolved air flotation water purification device according to claim 1, characterized in that: The precipitation device can be arranged in the separation zone (52), and the flocculation effect is strengthened.

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