Dynamic aeration and scum scraping air flotation machine

Abstract

The invention relates to the technical field of air floatation sewage treatment equipment, and provides a dynamic aeration and scum scraping air floatation machine which comprises an air floatation tank, a scum scraping device and a dissolved air release pipeline, and the moving direction of a scum scraping plate is configured to be opposite to the flowing direction of water; the dissolved air release pipeline comprises a main pipe, a plurality of branch pipes, a plurality of dissolved air release heads arranged on the branch pipes, and dynamic release valves arranged at the joints of the main pipe and the branch pipes; a guide column is connected below the slag scraping plate, and a trigger block is fixedly connected below the guide column; the trigger block is configured as follows: when the slag scraping plate moves to a preset position, the trigger block below the slag scraping plate synchronously triggers the three dynamic release valves arranged in the length direction of the air floatation tank; the valve opening degrees of the three synchronously triggered dynamic release valves are sequentially increased along the moving direction of the scum scraping plate, and aeration and scum scraping are synchronously performed in the same air floatation tank, so that water flow sequentially goes through a complete flow of scum generation by high aeration, scum lifting by middle aeration and scum enrichment by zero aeration.

Description

Technical Field

[0001] The present invention relates to the technical field of air flotation sewage treatment equipment, and particularly relates to an air flotation machine with dynamic aeration and scum scraping. Background Art

[0002] Aeration and scum scraping are common steps in air flotation sewage treatment. In traditional water treatment air flotation processes, such as the "composite impeller air flotation machine" disclosed in the Chinese utility model patent with the application number CN99243522.6, the aeration and scum scraping links are usually separated and realized in adjacent different pool bodies. This is because the aeration process relies on high-intensity dissolved gas release to form a turbulent flow field, promoting sufficient collision and adhesion between microbubbles and suspended pollutants (such as flocs) to generate a scum layer. This process requires sufficient fluid disturbance intensity to improve the bubble-pollutant contact efficiency, while the scum scraping process requires a stable static water environment to avoid the fragmentation, swirling settlement, or diffusion of the scum layer caused by water flow turbulence, otherwise the scraping efficiency will be significantly reduced. This results in the need for a multi-pool series structure for existing air flotation pools, which increases the infrastructure cost. In addition, during the transfer of pollutants from the aeration tank to the scum scraping tank, due to the extended hydraulic retention time, some scum redeposits due to bubble rupture; to maintain the stability of the scum, it is often necessary to overdose the dissolved gas volume, causing energy waste. Summary of the Invention

[0003] (I) Technical Problems to be Solved

[0004] In view of the deficiencies of the prior art, the present invention provides an air flotation machine with dynamic aeration and scum scraping, which overcomes the deficiencies of the prior art, is reasonably designed, has a compact structure, and solves the problem that the aeration and scum scraping of existing air flotation machines cannot be carried out in the same air flotation pool.

[0005] (II) Technical Solutions

[0006] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0007] The present invention provides an air flotation machine with dynamic aeration and scum scraping, including an air flotation pool, a scum scraping device arranged on the top of the air flotation pool, and a dissolved gas release pipeline. The scum scraping device includes a transmission belt driven by a motor and scum scraping plates fixed at equal intervals on the transmission belt. The motor drives the transmission belt to drive the scum scraping plates to rotate circularly above the air flotation pool to scrape the scum on the water surface in the air flotation pool.

[0008] In the air flotation pool, the moving direction of the scum scraping plate in contact with the water surface is configured to be opposite to the water flow direction;

[0009] The dissolved gas release pipeline includes a main pipe, a number of branch pipes connected to the side of the main pipe at equal intervals, a number of dissolved gas release heads arranged on each branch pipe, and a dynamic release valve arranged at the connection node between the main pipe and each branch pipe;

[0010] A guide post is connected below the slag scraping plate, and a trigger block is fixedly connected below the guide post; the trigger block is configured such that when the slag scraping plate moves to a preset position, the trigger block below it synchronously triggers three dynamic release valves arranged along the length direction of the dissolved air flotation tank; the valve openings of the three synchronously triggered dynamic release valves increase sequentially along the moving direction of the slag scraping plate.

[0011] Preferably, the trigger block is an upper wedge block, and the lower surface of the upper wedge block is a wedge-shaped inclined surface that gradually rises along the moving direction of the slag scraping plate;

[0012] The dynamic release valve includes a connecting pipe, a valve pipe communicated above the connecting pipe, a valve stem slidably arranged axially in the valve pipe, a lower wedge block fixedly connected to the top end of the valve stem, a fixing plate fixed above the outer side of the valve pipe, a guide rod fixedly connected to the bottom of the lower wedge block, a limiting plate fixedly connected to the bottom end of the guide rod, and a compression spring sleeved outside the guide rod; wherein, the upper surface of the lower wedge block is configured to be matched and fitted with the wedge-shaped inclined surface of the upper wedge block, a guide hole is formed on the surface of the fixing plate, the guide rod passes through the guide hole and is in sliding fit with the guide hole, and two ends of the compression spring respectively abut against the upper surface of the fixing plate and the lower surface of the lower wedge block;

[0013] The valve stem adjusts the insertion depth of its lower end in the connecting pipe through axial displacement to control the flow cross-sectional area of the dissolved air water.

[0014] Preferably, the bottom of the valve stem is conical, and a valve seat matched with the conical bottom is arranged in the connecting pipe; when the valve stem moves downwards, the annular gap cross-sectional area between the conical bottom and the valve seat decreases with the decrease of the insertion depth.

[0015] Preferably, an annular groove is formed on the outer periphery of the valve stem, and a piston ring for sealing is embedded in the annular groove.

[0016] Preferably, the trigger block includes a horizontal plate and three spaced-apart photoelectric emitters fixedly connected to the bottom surface of the horizontal plate;

[0017] The dynamic release valve is an electromagnetic proportional valve, and a photoelectric receiver corresponding to the photoelectric emitter is arranged on the electromagnetic proportional valve;

[0018] The control ends of the photoelectric emitter, the photoelectric receiver and the electromagnetic proportional valve are all connected to an external controller;

[0019] When the photoelectric receiver receives the signal of the corresponding photoelectric emitter, the controller adjusts the opening of the corresponding electromagnetic proportional valve according to a preset gradient value.

[0020] Preferably, the slag scraping surface of the slag scraping plate is gradually inclined upward with respect to the horizontal plane along its moving direction; the lower edge of the slag scraping plate is within the vertical projection range of the edge of the trigger block below it.

[0021] Preferably, a slag collection pool is separated on one side of the flotation tank by a partition board. The upper edge of the partition board is lower than the top height of the side wall of the flotation tank. The water inlet pipe of the sewage passes through the partition board and extends into the flotation tank, and its water outlet faces the side of the flotation tank where the slag scraping device is located.

[0022] (III) Beneficial effects

[0023] The embodiment of the present invention provides a flotation machine for dynamic aeration and scum scraping. It has the following beneficial effects:

[0024] In the present invention, during the movement of the slag scraping plate, a three-stage gradient aeration area distributed along the slag scraping path is synchronously triggered. Among them, the opening degree of the PA valve in the first-stage aeration area is the largest, forming a strong turbulent flow and a dense bubble flow to ensure the efficient capture of pollutants by microbubbles. The opening degree of the PB valve in the second-stage aeration area decreases, and the amount of bubbles is moderately reduced to form a stable upward flow to lift the scum layer and avoid the destruction of the turbulent flow. The opening degree of the PC valve in the third-stage aeration area is the smallest, maintaining the stability of the liquid surface flow field and creating a static water environment for slag scraping. In the same flotation tank, aeration and slag scraping are carried out synchronously, enabling the water flow to sequentially experience the complete process of "high aeration to generate scum, medium aeration to lift scum, and zero aeration to enrich scum", reducing the overall volume of the flotation tank. The aeration and slag scraping are linked in real time with a fast response speed, avoiding the problem of scum settlement during the traditional process of aeration followed by slag scraping, and improving the effect of scum cleaning. At the same time, in the present invention, gradient zoning is carried out in a single flotation tank, reducing the volume of the overall device, and trigger-type gradient aeration is adopted, reducing the dissolved air demand and energy consumption. Description of the drawings

[0025] Figure 1 It is a three-dimensional structural schematic diagram of the present invention;

[0026] Figure 2 is Figure 1 a partial enlarged view of part A in

[0027] Figure 3 is Figure 1 a side view of

[0028] Figure 4 is Figure 3 a partial enlarged view of part B in

[0029] Figure 5 a structural schematic diagram of an embodiment of the dynamic release valve;

[0030] Figure 6 is a matching schematic diagram of the trigger block and another embodiment of the dynamic release valve;

[0031] Figure 7 It is a schematic structural diagram of the connection between the slag scraping plate and the upper wedge block.

[0032] In the figure: 1. Dissolved air flotation tank; 2. Slag scraping device; 21. Motor; 22. Transmission belt; 23. Slag scraping plate; 24. Guide post; 25. Trigger block; 25a. Upper wedge block; 25b1. Horizontal plate; 25b2. Photoelectric emitter; 3. Dissolved air release pipeline; 31. Main pipe; 32. Branch pipe; 33. Dissolved air release head; 34. Dynamic release valve; 34a1. Connecting pipe; 34a2. Valve pipe; 34a3. Valve rod; 34a31. Annular groove; 34a32. Piston ring; 34a4. Lower wedge block; 34a5. Fixed plate; 34a51. Guide hole; 34a6. Guide rod; 34a7. Limiting plate; 34a8. Compression spring; 34a9. Valve seat; 34b1. Electro-hydraulic proportional valve; 34b2. Photoelectric receiver; 4. Partition plate; 5. Slag collection tank. Specific implementation manners

[0033] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Referring to the attached Figures 1-7 , it includes a dissolved air flotation tank 1, a slag scraping device 2 arranged on the top of the dissolved air flotation tank 1, and a dissolved air release pipeline 3. The slag scraping device 2 includes a transmission belt 22 driven by a motor 21 and slag scraping plates 23 fixed at equal intervals on the transmission belt 22. The motor 21 drives the transmission belt 22 to drive the slag scraping plates 23 to rotate circularly above the dissolved air flotation tank 1 to scrape the floating slag on the water surface in the dissolved air flotation tank 1; the dissolved air release pipeline 3 releases microbubbles in the dissolved air flotation tank 1 to fully collide and adhere with suspended pollutants (flocs) to form floating slag.

[0035] In the present invention, in the dissolved air flotation tank 1, the moving direction of the slag scraping plate 23 in contact with the water surface is configured to be opposite to the water flow direction, that is, the slag scraping plate 23 scrapes the floating slag in the opposite direction of the water flow movement. The moving speed of the slag scraping plate 23 is 0.1 - 0.3 m / s; the reverse movement of the slag scraping plate 23 against the water flow forms a "squeezing effect", and the floating slag is compressed and thickened under the action of the scraping force of the scraper and the reverse resistance of the water flow, which is beneficial to the enrichment of the floating slag.

[0036] Preferably, a slag collecting pool 5 is separated from one side of the flotation pool 1 by a partition 4. The upper edge of the partition 4 is lower than the top height of the side wall of the flotation pool 1 to form an overflow weir structure near the top of the pool wall. The sewage inlet pipe passes through the partition 4 and extends into the flotation pool 1, and its outlet faces the side of the flotation pool 1 where the scraper device 2 is located. When the scraper plate 23 pushes the enriched and thickened slag to the partition 4 along the length of the pool body against the water flow, the slag can smoothly climb over the partition 4 under the action of the thrust and overflow into the slag collecting pool 5. At the same time, the water inlet direction of the sewage inlet pipe is configured in the opposite direction of the scraper direction, so that the sewage part with the highest concentration of suspended impurities that has just entered the flotation pool 1 can be quickly contacted and processed by the scraper plate 23 closest to the slag collecting pool 5, which greatly shortens the retention and diffusion time of pollutants in the pool, avoids polluting the treated area or increasing the subsequent treatment load, and effectively improves the system's tolerance to water inlet load fluctuations and overall treatment efficiency.

[0037] The dissolved air release pipeline 3 includes a main pipe 31, a plurality of branch pipes 32 connected to the side of the main pipe 31 at equal intervals, a plurality of dissolved air release heads 33 arranged on each branch pipe 32, and a dynamic release valve 34 arranged at the connection node between the main pipe 31 and each branch pipe 32. Preferably, the dissolved air release heads 33 are staggered on the branch pipes 32, and the distance between adjacent dissolved air release heads 33 is 2-3 times the diameter of the dissolved air release heads 33, so as to form a densely distributed aeration area in the flotation tank 1;

[0038] A guide column 24 is connected below the scraper plate 23, and a trigger block 25 is fixedly connected below the guide column 24; the trigger block 25 is configured as follows: when the scraper plate 23 moves to a preset position, the trigger block 25 below it synchronously triggers three dynamic release valves 34 arranged along the length direction of the flotation tank 1, wherein the preset position is a working position where the trigger plate can dynamically release the valve 34 and the scraper plate 23 synchronously scrapes the debris on the water surface.

[0039] The scraping surface of the scraper plate 23 is gradually inclined upward relative to the horizontal plane along its moving direction. Preferably, the inclination angle of the scraper plate 23 is 8°-15°, which is conducive to the enrichment of scum. The lower edge of the scraper plate 23 is within the vertical projection range of the edge of the trigger block 25 below it, ensuring that the trigger block 25 below the scraper plate 23 can always be driven and accurately positioned during the movement of the scraper plate 23, thereby ensuring that the trigger block 25 can accurately reach and trigger the dynamic release valve 34 at the preset position.

[0040] Among them, the valve openings of the three synchronously triggered dynamic release valves 34 increase sequentially along the moving direction of the slag scraping plate 23. Thus, three gradient bubble density aeration zones are formed from near to far below the slag scraping plate 23, namely the primary aeration zone PA which is farthest from the front side of the slag scraping plate 23, the tertiary aeration zone PC which is closest to the front side of the slag scraping plate 23, and the secondary aeration zone PB which is located between the primary aeration zone PA and the tertiary aeration zone PC. Among them, in the primary aeration zone PA, the valve opening of the dynamic release valve 34 is the largest, forming a dense bubble flow. The strong turbulence promotes a large number of microbubbles to adhere to the suspended pollutants to form scum; in the secondary aeration zone PB, the valve opening of the dynamic release valve 34 is in the middle, and the aeration volume is smaller than that in the primary aeration zone PA. An appropriate amount of bubbles form a stable bubble upward flow in this area, avoiding the generation of turbulence, maintaining the amount of bubbles on the surface of the scum, avoiding the destruction of the scum layer by turbulence, reducing the swirling settlement of the scum, and keeping the scum on the water surface; the tertiary aeration zone PC is close to the slag scraping plate 23, and the aeration volume is extremely small or zero, maintaining the stability of the flow field on the liquid surface, avoiding the re-dispersion of the scum due to turbulence, creating a static water environment to ensure the stable enrichment of the scum, and facilitating scraping. The area covered by the moving track of the slag scraping plate 23 all experiences a complete process of "high aeration to generate scum, medium aeration to lift the scum, and zero aeration to enrich the scum". The aeration and slag scraping are linked in real time, with a fast response speed, avoiding the problem of scum settlement during the traditional process of scraping the scum after aeration, and improving the effect of scum cleaning. At the same time, in the present invention, gradient zoning is carried out in a single air flotation tank 1, reducing the volume of the overall device, and adopting trigger-type gradient aeration, reducing the dissolved air demand and energy consumption.

[0041] In addition, during a single slag scraping stroke when the slag scraping plate 23 moves from one side of the air flotation tank 1 to the other side, the trigger block 25 under the guide post 24 synchronously displaces, and three groups of dynamic release valves 34 at different positions will be continuously triggered along the way. Each time a group of valves is triggered, a new PA, PB, PC gradient aeration zone is generated directly in front of the current slag scraping plate 23. The width of this gradient aeration zone is relative to the spacing of the slag scraping plate 23, which enables the water body to undergo multiple cycle treatments, that is, a single slag scraping stroke completes N "aeration - scraping" sub-cycles (N = the number of triggered valve groups). The suspended substances experience repeated bubble capture, and the removal rate of fine particles (such as emulsified oil and colloid) is significantly improved, realizing dynamic continuous aeration and cyclic cleaning of the water body suspended substances.

[0042] In the present invention, multiple groups of dynamic release valve groups arranged along the length of the pool (each group includes three dynamic release valves 34 corresponding to the PA, PB, and PC zones) can operate independently without interference. Since the water flow direction is opposite to the moving direction of the slag scraping plate 23 (i.e., flowing from the PA zone to the PC zone), the dense bubble flow released in the PA zone, under the action of strong turbulence, mainly diffuses and rises backward with the water flow and basically does not flow backward and forward to the PC zone on other trigger valve groups. There is a physical distance (with the PB zone in between) between the high-intensity PA zone and the low / non-aerated PC zone above the branch pipes connected to the dynamic release valve 34 triggered by the same trigger plate, which limits the direct lateral diffusion range of the bubbles. The PB zone in the middle uses a medium aeration intensity, and the amount of its bubbles is significantly lower than that in the PA zone. Moreover, in the water treatment flotation process control, the water flow velocity is usually low, and the horizontal migration distance of the bubbles in the water flow direction is relatively short compared to the distance between the aeration intervals within the group. Most of the bubbles have completed floating and capturing pollutants in the PA and PB zones, and the amount of bubbles diffusing to the PC zone of this group is very small. Therefore, the area covered by the moving trajectory of the slag scraping plate 23 can all experience the complete process of "high aeration to generate scum, medium aeration to lift the scum, and zero aeration to enrich the scum".

[0043] In addition, by controlling the moving speed of the slag scraping plate 23, the moving speed of the trigger block 25 can be synchronously changed, thereby adjusting the action time (i.e., the dissolved air release duration) of each dynamic release valve 34 in the triggered state, so as to optimize the dissolved air consumption while ensuring the aeration and slag scraping effects, and achieve the purpose of energy saving.

[0044] As a specific embodiment of the present invention, Figure 3 、 Figure 4 、 Figure 5 、 Figure 7 shows a specific combined use form of the trigger block 25 and the dynamic release valve 34.

[0045] Among them, the trigger block 25 is an upper wedge block 25a, and the lower surface of the upper wedge block 25a is a wedge-shaped inclined surface that gradually rises along the moving direction of the slag scraping plate 23;

[0046] The dynamic release valve 34 includes a connecting pipe 34a1, a valve pipe 34a2 communicating above the connecting pipe 34a1, a valve stem 34a3 slidably arranged axially in the valve pipe 34a2, a lower wedge block 34a4 fixedly connected to the top end of the valve stem 34a3, a fixing plate 34a5 fixed above the outer side of the valve pipe 34a2, a guide rod 34a6 fixedly connected to the bottom of the lower wedge block 34a4, a limiting plate 34a7 fixedly connected to the bottom end of the guide rod 34a6, and a compression spring 34a8 sleeved outside the guide rod 34a6. Among them, the upper surface of the lower wedge block 34a4 is configured to fit and match with the wedge-shaped inclined surface of the upper wedge block 25a. A guide hole 34a51 is formed on the surface of the fixing plate 34a5. The guide rod 34a6 passes through the guide hole 34a51 and is slidably matched with the guide hole 34a51 to ensure the vertical movement of the valve stem 34a3 and prevent skew jamming. The two ends of the compression spring 34a8 respectively abut against the upper surface of the fixing plate 34a5 and the lower surface of the lower wedge block 34a4. The compression spring 34a8 provides a reset force to enable the valve stem 34a3 to reset to the highest position to maximize the valve opening. The upper wedge block 25a converts the horizontal displacement into vertical pressure to trigger the adjustment of the valve opening. The lower wedge block 34a4 receives the inclined surface thrust and conducts the mechanical energy to the valve stem 34a3 to cause the valve stem 34a3 to displace axially.

[0047] The valve stem 34a3 adjusts the insertion depth of its lower end in the connecting pipe 34a1 through axial displacement to control the flow cross-sectional area of the dissolved air water.

[0048] In this embodiment, the bottom of the valve stem 34a3 is conical, and a valve seat 34a9 matching the conical bottom is provided in the connecting pipe 34a1. When the valve stem 34a3 moves downward, the annular gap cross-sectional area between the conical bottom and the valve seat 34a9 decreases with the insertion depth.

[0049] Preferably, an annular groove 34a31 is formed on the outer periphery of the valve stem 34a3, and a piston ring 34a32 for sealing is embedded in the annular groove 34a31.

[0050] During the horizontal movement of the slag scraping plate 23, the inclined surface of the upper wedge block 25a squeezes the lower wedge block 34a4 to drive the valve stem 34a3 to linearly displace vertically downward. The deeper the insertion depth of the lower end of the valve stem 34a3 in the connecting pipe 34a1, the smaller the flow cross-sectional area of the dissolved air water and the less the amount of bubble release. Since the lower surface of the upper wedge block 25a is a wedge-shaped inclined surface that gradually rises along the moving direction of the slag scraping plate 23, the downward displacement of the lower wedge block 34a4 contacted by the upper wedge block 25a is smaller in the more forward side of the moving direction, and the flow cross-sectional area of the dissolved air water is larger. Among the three dynamic release valves 34 contacted by the upper wedge block 25a, three-stage aeration regions PA, PB, and PC are formed in sequence from far to near on the forward side of their moving direction.

[0051] As another specific embodiment of the present invention, Figure 6Another specific form of combined use of the trigger block 25 and the dynamic release valve 34 is shown.

[0052] Among them, the trigger block 25 includes a horizontal plate 25b1 and three photoelectric emitters 25b2 that are fixedly connected to the bottom surface of the horizontal plate 25b1 and are distributed at intervals.

[0053] The dynamic release valve 34 is an electromagnetic proportional valve 34b1, and a photoelectric receiver 34b2 corresponding to the photoelectric emitter 25b2 is arranged on the electromagnetic proportional valve 34b1.

[0054] The control ends of the photoelectric emitter 25b2, the photoelectric receiver 34b2 and the electromagnetic proportional valve 34b1 are all connected to an external controller.

[0055] When the photoelectric receiver 34b2 receives the signal of the corresponding photoelectric emitter 25b2, the controller adjusts the opening degree of the corresponding electromagnetic proportional valve 34b1 according to a preset gradient value.

[0056] In this embodiment, a non-contact signal is used to replace mechanical contact. The three photoelectric emitters 25b2 correspond to three-stage aeration zones: when the photoelectric emitter 25b2 passes above the solenoid valve, different opening degree values are preset by the controller to achieve gradient control of PA, PB, and PC. The biggest difference between this photoelectric scheme and the mechanical scheme is that the opening degree is programmable and is no longer limited by the physical structure of the inclined plane. The photoelectric head seal design is more resistant to sludge adhesion than mechanical sliding parts. In addition, the controller can modify the opening degree value at any time to cope with water quality changes, and the adjustment flexibility is high. An alarm can be given immediately when the signal is interrupted, while it is difficult to detect in real time when a mechanical valve is stuck, and the reliability is high.

[0057] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A flotation machine with dynamic aeration and scum scraping, comprising a flotation tank (1), a scum scraping device (2) arranged at the top of the flotation tank (1), and a dissolved air release pipeline (3). The scum scraping device (2) includes a transmission belt (22) driven by a motor (21), and scum scraping plates (23) fixedly arranged on the transmission belt (22) at equal intervals. The motor (21) drives the transmission belt (22) to drive the scum scraping plates (23) to rotate circularly above the flotation tank (1) to scrape the scum on the water surface in the flotation tank (1). It is characterized in that: Inside the flotation tank (1), the moving direction of the scum scraping plate (23) in contact with the water surface is configured to be opposite to the water flow direction; The dissolved air release pipeline (3) includes a main pipe (31), a number of branch pipes (32) connected to the side of the main pipe (31) at equal intervals, a number of dissolved air release heads (33) arranged on each branch pipe (32), and a dynamic release valve (34) arranged at the connection node of the main pipe (31) and each branch pipe (32); A guide post (24) is connected below the scum scraping plate (23), and a trigger block (25) is fixedly connected below the guide post (24); the trigger block (25) is configured such that when the scum scraping plate (23) moves to a preset position, the trigger block (25) below it synchronously triggers three dynamic release valves (34) arranged along the length direction of the flotation tank (1); the valve openings of the three synchronously triggered dynamic release valves (34) increase sequentially along the moving direction of the scum scraping plate (23).

2. The flotation machine with dynamic aeration and scum scraping according to claim 1, characterized in that: The trigger block (25) is an upper wedge block (25a), and the lower surface of the upper wedge block (25a) is a wedge-shaped inclined surface that gradually rises along the moving direction of the scum scraping plate (23); The dynamic release valve (34) includes a connecting pipe (34a1), a valve pipe (34a2) communicating above the connecting pipe (34a1), a valve rod (34a3) slidably arranged axially in the valve pipe (34a2), a lower wedge block (34a4) fixedly connected to the top end of the valve rod (34a3), a fixing plate (34a5) fixed above the outer side of the valve pipe (34a2), a guide rod (34a6) fixedly connected to the bottom of the lower wedge block (34a4), a limiting plate (34a7) fixedly connected to the bottom end of the guide rod (34a6), and a compression spring (34a8) sleeved outside the guide rod (34a6); wherein, the upper surface of the lower wedge block (34a4) is configured to match and fit with the wedge-shaped inclined surface of the upper wedge block (25a), a guide hole (34a51) is formed on the surface of the fixing plate (34a5), the guide rod (34a6) passes through the guide hole (34a51) and is in sliding fit with the guide hole (34a51), and the two ends of the compression spring (34a8) respectively abut against the upper surface of the fixing plate (34a5) and the lower surface of the lower wedge block (34a4); The valve stem (34a3) adjusts the insertion depth of its lower end in the connecting pipe (34a1) through axial displacement to control the flow cross-sectional area of the dissolved air water.

3. The dissolved air flotation machine for dynamic aeration and scum scraping according to claim 2, wherein: The bottom of the valve stem (34a3) is conical, and a valve seat (34a9) matching the conical bottom is arranged in the connecting pipe (34a1); when the valve stem (34a3) moves downward, the annular gap cross-sectional area between the conical bottom and the valve seat (34a9) decreases with the insertion depth.

4. The dissolved air flotation machine for dynamic aeration and scum scraping according to claim 2, wherein: An annular groove (34a31) is formed on the outer periphery of the valve stem (34a3), and a piston ring (34a32) for sealing is embedded in the annular groove (34a31).

5. The dissolved air flotation machine for dynamic aeration and scum scraping according to claim 1, wherein: The trigger block (25) includes a horizontal plate (25b1) and three photoelectric emitters (25b2) which are fixedly connected to the bottom surface of the horizontal plate (25b1) and are distributed at intervals; The dynamic release valve (34) is an electromagnetic proportional valve (34b1), and a photoelectric receiver (34b2) corresponding to the photoelectric emitter (25b2) is arranged on the electromagnetic proportional valve (34b1); The control ends of the photoelectric emitter (25b2), the photoelectric receiver (34b2) and the electromagnetic proportional valve (34b1) are all connected to an external controller; When the photoelectric receiver (34b2) receives the signal of the corresponding photoelectric emitter (25b2), the controller adjusts the opening degree of the corresponding electromagnetic proportional valve (34b1) according to a preset gradient value.

6. A flotation machine for dynamic aeration and scum scraping according to any one of claims 1-5, characterized in that: The scum scraping surface of the scum scraping plate (23) is gradually inclined upward along its moving direction relative to the horizontal plane; the lower edge of the scum scraping plate (23) is within the vertical projection range of the edge of the trigger block (25) below it.

7. The air flotation machine for dynamic aeration and scum scraping according to claim 6, characterized in that: One side of the dissolved air flotation tank (1) is separated into a scum collection tank (5) by a partition plate (4), the upper edge of the partition plate (4) is lower than the top height of the side wall of the dissolved air flotation tank (1), the water inlet pipe of the sewage passes through the partition plate (4) and extends into the dissolved air flotation tank (1), and its water outlet faces the side of the dissolved air flotation tank (1) where the scum scraping device (2) is located.

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